Cosmo-26

Contribution List

294. "CoDE-4: A Phenomenological Framework for Cross-Epoch Cosmological Consistency"

Siddharth Sathish Kumar (Independent Researcher)

Poster

CoDE-4 (Cosmic Dynamical Expansion Framework v1.0)

Cross-Epoch Consistent Resolution of the H₀ Tension with Coupled Expansion–Growth Dynamics

Model Status and Scope

CoDE-4 is a phenomenological cosmology framework designed to test whether modest early-time expansion modifications combined with scale-dependent structure-growth coupling can reconcile the Hubble-parameter discrepancy...

167. A Critique on Formulating Local Theories of Gravity from Non-Extensive Entropies

JOHN BAYRON ORJUELA-QUINTANA (UNIVERSIDAD DEL VALLE)

Poster

The thermodynamic emergence of local spacetime dynamics is inextricably tied to the strict extensivity of the holographic area law. While quantum gravity candidates often motivate generalized, non-extensive entropy-area relations for black holes, substituting these into Jacobson's framework to derive modified gravity theories is generically inconsistent. We argue that any departure from...

322. A Disformal Affair: How Dark Matter Mimics Lorentz Violation

Mr Apostolos Tsampodimos (FTMC)

Dark Energy / Modified Gravity

Talk

We study the effects of general disformal metric transformations on fermionic fields, showing that the Dirac action acquires additional kinetic and axial-current couplings. When the sourcing field takes a nontrivial background value, apparent Lorentz-violating effects arise, which we classify within an effective field theory. For scalar and vector ultralight dark matter, precision tests of...

276. A framework for efficient map-based simulations to mitigate instrumental systematics for CMB surveys

Magdy Morshed (INFN Ferrara)

Cosmic Microwave Background

Talk

The current and future observations of the CMB are expected to reach unprecedented sensitivity to place stringent constraints on both cosmological parameters and fundamental physics. The ground-based Simons Observatory Large Aperture Telescope started observations last year, and will provide the most sensitive small-scale CMB measurements. A tight control over instrumental systematics is...

151. A Minimal Axio-dilaton Dark Sector

Anne Davis

Dark Energy / Modified Gravity

Talk

Axio-dilaton models provide a well-motivated minimal class of models for which self-interactions can be explored. This minimal model can successfully describe both Dark Matter and Dark Energy. The axion is the Dark Matter and the dilaton is the Dark Energy — and that they robustly predict several new phenomena for the CMB and structure formation that can be sought in observations. These...

109. A new look at particle production from a sharp turn of the inflationary trajectory

Jakub Kalkowski (University of Warsaw)

Poster

During expansion in the de Sitter spacetime, particle production takes place from the perspective of the observer for whom the vacuum state was defined in the past.
To account for this phenomenon, we use a newly developed formalism of
Nicolas Parra et al. [arXiv:2410.13843v2], which greatly simplifies the analysis.
We derive the predictions for the number density of particles produced at...

221. A Parameter Scan of Current-Carrying Cosmic Strings

Ricarda Heilemann (Centro de Astrofísica da Universidade do Porto)

Early Universe

Talk

Cosmic string networks are expected to form during symmetry-breaking phase transitions in the early Universe via the Kibble mechanism and arise naturally in many extensions of the Standard Model. In several such scenarios, string networks can carry additional degrees of freedom, such as charges and currents, leading to so-called current-carrying or superconducting cosmic strings. These...

224. A self-calibration method of imaging systematics using power spectrum and bispectrum

Qianran Xia (University of Michigan)

Methods / Statistical Inference / Machine Learning

Talk

Imaging systematics in galaxy surveys generate large-scale angular selection effects that can contaminate measurements of primordial non-Gaussianity. We develop a analytical framework to propagate two-dimensional imaging templates into three-dimensional power spectrum and bispectrum observables. In this approach, angular templates are embedded into radial survey shells, and their effects on...

164. A Tensorised Analytic Framework for Fast, Differentiable Lensing Angular Power Spectra

Yun-Hao Zhang (Leiden University)

Poster

Weak gravitational lensing is now one of the most powerful probes of cosmological parameters and the nature of dark matter and dark energy. Stage-IV analyses will require rapid evaluation of summary statistics across wide angular scales and many tomographic bins, to sample efficiently the high-dimensional parameter spaces of modern likelihoods.
I will present a new mathematical framework that...

156. Adaptive emulation for next-generation cosmological inference

Maria Tsedrik (University of Edinburgh)

Methods / Statistical Inference / Machine Learning

Talk

The unprecedented precision of recent galaxy surveys and CMB experiments is transforming cosmology but at a cost. As modelling frameworks grow more sophisticated, the number of nuisance parameters has surged, while emerging tensions with the standard cosmological model motivate extensions in cosmological parameters as well. Combined with computationally expensive models, these developments...

160. Addressing Cosmological Tensions with ML-Guided Modified-Gravity Searches

Linus Thummel (University of Edinburgh)

Dark Energy / Modified Gravity

Talk

Modifications of General Relativity have been widely studied to alleviate cosmological tensions. Most of these models lead to an effective strengthening of gravity and enhanced growth. However, the S8 tension - arising from weak-lensing observations that suggest less structure formation than predicted by ΛCDM - points to a different scenario.
In this talk, I will present a method to design...

9. AI/ML Techniques for Model-Independent Cosmological Analysis

Mr Rahul Shah (Indian Statistical Institute, Kolkata)

1

Dark Energy / Modified Gravity

Talk

Machine learning is increasingly shaping cosmological analyses, though its impact depends critically on careful validation and physically interpretable use. In this talk, I will outline several AI/ML approaches for model-independent cosmological inference, with an emphasis on how data-driven methods can complement more traditional statistical techniques. I will discuss...

69. All-Tree Massive Cosmological Correlators from Spectral Gluing

Denis Werth (Max Planck Institute for Physics)

Inflation / Primordial Perturbations

Talk

In this talk, I will present a novel framework to compute massive tree-level cosmological correlators based on "spectral gluing". The central idea is to decompose exchange diagrams into elementary vertex functions and systematically reconstruct arbitrary tree graphs through an algorithmic gluing procedure involving spectral integration. This approach provides a unifying and efficient method to...

270. Ambiguities and uncertainties in gravitational dark matter production

Álvaro Parra-López (University of Oslo)

Inflation / Primordial Perturbations

Talk

The persistent absence of non-gravitational dark matter signals has increased interest in candidates that interact extremely weakly with the Standard Model—if at all. (Non-perturbative) gravitational particle production provides an unavoidable mechanism for generating such dark matter via the expansion of spacetime. However, predicting the exact relic abundance is subject to significant...

22. An open effective field theory of inflation with dynamical gravity

Perseas Christodoulidis (Ewha Womans Universtity)

Inflation / Primordial Perturbations

Talk

We construct a gravitational open extension of the effective field theory of inflation in the Schwinger-Keldysh framework. While physical symmetries allow many open operators in the Schwinger-Keldysh action, most of them overconstrain the equations of motion, yielding inconsistent dynamics. We identify the minimal open operators compatible with propagating scalar and tensor modes and build the...

302. Anchoring the Hubble Constant with Cosmic Distance Duality

Yashi Tiwari (Institute of Theoretical Physics, Chinese Academy of Sciences)

Poster

The Cosmic Distance Duality Relation (CDDR) is a fundamental geometric relation that connects the luminosity distance and the angular diameter distance at a given redshift. It holds in any metric theory of gravity with standard photon propagation and number conservation, and is therefore independent of any specific cosmological model. Since distance measurements form the basis of our...

136. Anisotropic CMB spectral distortions from dark photon conversion

Sara Evangelista (University of Manchester)

Early Universe

Talk

The dark photon is the gauge boson of a hypothetical dark sector, representing a minimal extension to the Standard Model. This massive particle interacts with the visible photon through kinetic mixing and has been widely studied as a dark matter candidate. We consider a scenario in which an initially unpopulated dark sector is populated via photon–dark photon conversion prior to recombination,...

203. Anisotropic Universes in Light of Background Cosmological Observations

Cesar A. Valenzuela-Toledo (Departamento de Física, Universidad del Valle)

Dark Energy / Modified Gravity

Talk

The cosmological principle is a cornerstone of the standard cosmological model. However, recent observations suggest potential deviations from this assumption, hinting at a small anisotropic expansion. Such an expansion can arise from sources that break rotational invariance. A minimal realization of this scenario is described by a Bianchi I geometry, where the degree of anisotropy is...

72. Anti-ultralocality and plateau models of inflation

Joshua Shterenberg (Princeton University)

Inflation / Primordial Perturbations

Talk

Anti-ultralocality refers to the amplification of spatial gradients, inhomogeneities, and anisotropies during phases of decelerating expansion. The effect is driven by nonlinear general relativistic dynamics in the Einstein–scalar field system of equations. Previous numerical relativity studies have shown that, beginning with generic initial conditions following a big bang, this amplification...

210. Assessing baryonification for weak lensing observables

Andreas Nygaard (University of Zurich)

Large-Scale Structure

Talk

Baryonic physics introduces significant uncertainties in cosmological observables such as weak lensing statistics, while accurate predictions typically require computationally expensive hydrodynamical simulations. This limits the exploration of the parameter space in modern cosmological analyses. Baryonification methods provide a fast alternative by incorporating baryonic effects into dark...

243. Asymmetric Reheating of Dark QED

Simon Clery (Technical University of Munich (TUM))

Inflation / Primordial Perturbations

Talk

The reheating epoch following inflation sets the initial conditions
for the subsequent thermal history of the Universe, but remains
largely unconstrained prior to Big Bang nucleosynthesis. In many
extensions of the Standard Model, the inflaton may decay
simultaneously into visible and hidden sectors, leading to
non-standard cosmological histories. One possibility...

363. Audible Axion Magnetogenesis

Christopher Gerlach (Johannes Gutenberg University Mainz)

Primordial Magnetic Fields

Talk

Axion-like particles coupled to the Standard Model photon are able to simultaneously generate a gravitational wave background and primordial magnetic fields, providing a multi-messenger probe of a promising dark matter candidate.
Mechanisms like trapped misalignment can delay the onset of oscillations, inducing a period of supercooling in the early Universe. The supercooling then allows for...

255. Axion Detection With Coiled Optical Fibers

Tongxuan Zhang (LMU Munich and Max Planck Institute for Physics)

Dark Matter

Talk

We propose a novel interferometric approach to axion searches based on long, coiled optical fibers in an external magnetic field. Considering fiber boundary conditions and bending, I will show that in silica fibers the leading signal is a phase shift of the photon. A key observation is that the axion field will effectively get confined along the fiber, despite no direct interaction between...

53. Axion perturbation growth at low-temperature reheating

Paola Arias (Universidad Federico Santa María)

Dark Matter

Talk

We study the evolution of axion cold dark matter overdensities in low-temperature reheating cosmologies, focusing on the interplay between the temperature-dependent axion mass and the radiation background. We show that modes entering the horizon prior to both reheating and the onset of oscillations experience a significant enhancement driven by their coupling to radiation perturbations. This...

126. Balancing bias, baryons, and scale cuts in LSST $3\times2$pt analysis

Ottavia Truttero (University of Edinburgh)

Poster

Stage IV surveys such as LSST will probe deeply into the nonlinear regime, where systematic effects from galaxy bias and baryonic feedback become dominant and poorly constrained nuisance parameters can lead to degeneracies.
We perform a $3\times2$pt analysis for LSST Y1 and Y10 to investigate how modelling choices impact cosmological constraints. In particular, we explore the balance between...

4. Baryonified Lightcones: A Unified Framework for LSS–CMB Cross‑Correlation Cosmology

Michael Kovac (University of Manchester)

Cosmic Microwave Background

Talk

Understanding the impact of baryonic feedback on the matter distribution is a major challenge for precision cosmology, especially for analyses combining large-scale structure tracers with CMB secondary anisotropies. We recently showed that combining kinematic Sunyaev–Zel’dovich measurements from ACT with gas‑fraction data from eROSITA provides strong constraints on gas thermodynamics in...

121. Belle II excess and dark matter semi-annihilation

Dr Jongkuk Kim (Kangwon National University)

Dark Matter

Talk

In 2023, the Belle II Collaboration announced the observation of the
B→K+νν decay channel for the first time. This decay channel provides a clean signal with high precision in theoretical calculations. However, we encounter a 2.8σ deviation from the Standard Model prediction. To resolve this excess, we study a scalar dark matter model with local discrete Z_3 symmetry. Assuming dark...

55. Beyond CPL: Testing Dynamical Dark Energy with Extended Three-Parameter Models

Sonej Alam (Jamia Millia Islamia, New Delhi)

Poster

We introduce two three-parameter extensions of the minimal Akhtar–Hossain (mAH) dark energy parametrization, termed modified minimal AH (MmAH1 and MmAH2), which provide a smooth and bounded evolution of the dark energy equation of state while retaining $\Lambda$CDM as a limiting case. Using a joint analysis of the CMB compressed likelihood, DESI DR2 BAO, $H(z)$, redshift space distortions, and...

143. Black Hole QNMs in external tidal fields

Bruno Bucciotti (Arizona State University)

Gravitational Waves

Talk

Future gravitational-wave observatories, including next-generation ground-based detectors and LISA, will enable precision measurements of black hole quasi-normal mode frequencies. In realistic astrophysical settings, however, black holes are not perfectly isolated: surrounding environments, for example stars or dark matter, can source external tidal fields that deform the QNM spectrum. In this...

309. Bohmian Trajectories and Complex Thermodynamics of Quarkonium Oscillator in Conic Gravitational Space-Time

Alptuğ Karadoğan (Akdeniz University)

Poster

The study elucidates the quantum trajectories of the relativistic Quarkonium oscillator in conic gravitational field. First, the Klein-Gordon (KG) equation is solved with respect to the constrained metric, and the quantum dynamics are discussed around the asymptotic regimes. Afterwards, the energy spectrum is found for the examination of the bound states and scattering cases. Secondly, the...

56. Bouncing Cosmologies in Modified Gravity with Spacetime Torsion

Sonej Alam (Jamia Millia Islamia, New Delhi)

Poster

We explore the possibility of realizing a non-singular bounce in the early universe within the framework of modified gravity with spacetime torsion. In Einstein Cartan theory, torsion is embedded in the spacetime by adding an antisymmetric part in affine connection . We consider generalized version of the framework as $f(\bar{R})$, $\bar{R}$ being the scalar of the modified curvature tensor....

38. Bounds on Goldstone Dispersion Relations

Warin Patrick McBlain (SISSA)

Dark Energy / Modified Gravity

Talk

Using the analyticity properties of retarded Green's functions, we show that the Goldstone dispersion relations can be written in terms of ‘typically-real functions’: a well-known class of functions in Geometric Function Theory. This identification yields optimal two-sided bounds on Wilson coefficients of higher-derivative operators as explicit functions of the sound speed $c_s$. We test these...

23. Breaking the Hubble Constant Degeneracy in Time-Delay Lensing: A Sequential Filtering Analysis of Time-Delay Lenses in IllustrisTNG

Yiwei He (the University of Hong Kong)

Poster

The growing tension between early- and late-Universe measurements of the Hubble constant ($H_0$) has elevated time-delay cosmography to a primary probe of the expansion rate. However, the precision of this "one-step" method is fundamentally limited by the mass-sheet degeneracy (MSD) and model mis-specification. In this work, we present a systematic exploration of the $H_0$ likelihood surface...

320. Can a JWST-driven reionisation history be consistent with Planck’s optical depth and DESI’s total neutrinos mass constraints at once?

Enrico Specogna (University of Sheffield)

Neutrinos

Talk

In this talk we will look at a modification to the standard reionisation history through the lens of a model for the optical depth ($\tau$) that is motivated by the recent results by JWST, which find sources of ionising photons at redshifts larger than ever observed before. By using this JWST-driven model, which allows for a “bumpy” reionisation history that pushes $\tau$ to higher values as...

188. Can non-minimally coupled dark matter explain UDG kinematics?

Saboura sadat Zamani (University of Szczecin)

Poster

We investigate non-minimal coupling (NMC) between dark matter and gravity. NMC is a theoretical extension of general relativity where the gravitational potential is modified by dark matter density gradients.
We analyze three ultra-diffuse galaxies (UDGs) with contrasting dark matter fractions to test whether NMC produces observable effects on galactic scales. We perform spherical Jeans...

190. Can the Topology of the Universe Affect the CMB? A Path to Detection

Javier Carrón Duque (IFT)

Cosmic Microwave Background

Talk

We often assume that the Topology of the Universe is trivial (i.e., R³ if the Universe is flat), but there are actually 18 possible topologies that admit a flat FLRW metric, such as a 3D torus. I will explain how these topologies can introduce potentially measurable effects on the Cosmic Microwave Background (CMB), generally breaking statistical isotropy in a weak but predictable manner. This...

144. Charge distribution of Q-balls and cosmological implications

Dr Masahiro Kawasaki (University of Tokyo)

Early Universe

Talk

We perform three-dimensional lattice simulations to investigate the formation of gauge-mediation type Q-balls. For the first time, we obtain their broad charge distribution of the Q ball of this type. We then discuss the cosmological and astrophysical implications of this broad distribution. In particular, we study the formation of primordial black holes (PBHs) induced by Q-balls. We find that...

238. Classification of MHD Turbulence Regimes Based on Their Physical Evolution Laws

Yuri Yamashita (Nagoya University)

Poster

Magnetic turbulence has been suggested to be controlled either by Alfvénic dynamics or by magnetic reconnection, and the relative importance of these two mechanisms has remained an open question. In this work, we examine the physical processes that regulate the evolution of magnetic turbulence by means of numerical simulations. We consider maximally helical MHD turbulence in a magnetically...

122. Closing in on the EFTofDE with combined probes and nonlinear predictions

Neel Shah (University of Portsmouth)

Dark Energy / Modified Gravity

Talk

The EFT of Dark Energy (EFTofDE) is a theoretically well-motivated class of modified gravity models, able to explain observational hints for dynamical dark energy with further testable predictions for structure growth and lensing. I will discuss the merits and challenges of combining probes of linear perturbations and present state-of-the-art constraints on the EFTofDE by combining CMB, BAO,...

82. CMB birefringence from ultralight-axion string networks

Moira venegas villa

Cosmic Microwave Background

Talk

Axion-like particles (ALPs) can form a network of cosmic strings that persists after recombination and induces birefringence in the cosmic microwave background (CMB), rotating the plane of polarization of propagating photons. In this work, we analyze a high-resolution simulation of an axion string network generated using adaptive mesh refinement (AMR) techniques. By performing ray tracing...

48. Coherent and incoherent dark matter: A unified two-fluid approach

Alex Soto (Institute of Physics, Polish Academy of Science)

Dark Matter

Talk

We present from the Schwinger-Keldysh path integral formalism, equations for bosonic, non-relativistic and self-interacting dark matter. The equations can describe a two-fluid system composed of a coherent and an incoherent mixture, encompassing both CDM and Fuzzy Dark Matter in a unified way. The model incorporates new terms, such as the Lee-Huang-Yang correction, known in Cold Atom Physics,...

116. Coherent State Description of Gravitational Waves from Binary Black Holes

Akira Taniguchi (Kyushu University)

Gravitational Waves

Talk

Quantum mechanics provides the fundamental framework for describing nature, and gravitational waves from binary black holes should ultimately be understood within this framework. It is widely believed that classical gravitational waves correspond to coherent states, so any deviation would signal genuine quantum features of gravity.

In this talk, based on our recent work published in Phys....

159. Combining CMB lensing, galaxy clustering, and cosmic shear with 2- and 3-point statistics

Nicola Principi Cavaterra (Narodowe Centrum Badań Jądrowych (NCBJ))

Cosmic Microwave Background

Talk

The standard ΛCDM model has been remarkably successful, but it has recently being challenged by several tensions. The combination of galaxy surveys and CMB lensing is a powerful probe of the large-scale structure and a key tool for testing the ΛCDM model in the era of next-generation experiments. Upcoming galaxy surveys such as the Legacy Survey of Space and Time (LSST) and Euclid, together...

98. Compact star X-Ray-production through interactions with dark matter

Jaime Hoefken Zink (Narodowe Centrum Badań Jądrowych (NCBJ))

Dark Matter

Talk

Dark matter (DM) may naturally exhibit inelastic structure, with small mass splittings between states arising from symmetry breaking. In such scenarios, the lightest DM state can upscatter to a heavier state that subsequently decays semi-visibly, producing secondary photon fluxes. Compact objects—such as neutron stars and white dwarfs—provide efficient environments for these processes,...

234. Constraining baryonic feedback and cosmology from DES Y3 and Planck PR4 6x2pt data

Jiachuan Xu (Northeastern University)

Large-Scale Structure

Talk

We combine weak lensing, galaxy clustering, cosmic microwave background (CMB) lensing, and their cross-correlations (so-called 6$\times$2pt) to constrain cosmology and baryonic feedback scenarios using data from the Dark Energy Survey (DES) Y3 Maglim catalog and the Planck satellite PR4 data release. We include all data points in the DES Y3 cosmic shear two-point correlation function (2PCF)...

256. Constraining Beyond-CDM Models with an Effective Theory of the Lyman-α Forest

Tim-Leon Klocke (University of Oslo)

Dark Matter

Talk

In the age of precision cosmology, mapping the large-scale structure of the universe has the potential to reveal pieces of the puzzle that is the nature of dark matter. Most deviations from standard cold DM (CDM) models are confined to cosmologically small scales to not violate existing constraints. Thus, there is a fundamental need to have accurate models of the non-linear formation of...

217. Constraining cosmology with the Lyman-alpha forest

Olga Garcia Gallego (Institute of Astronomy, University of Cambridge)

Dark Matter

Talk

The Lyman-alpha forest is a powerful cosmological probe of matter density fluctuations in the weakly non-linear regime through the high redshift and underdense intergalactic medium (IGM). On small scales, the Lyman-alpha 1D flux power spectrum is uniquely sensitive to both the properties of dark matter and the complex gas dynamics driven by IGM photoheating during reionization, offering...

54. Constraining decaying dark matter with weak lensing higher-order statistics

Mariia Marinichenko (Leiden University)

Methods / Statistical Inference / Machine Learning

Talk

Stage IV weak lensing (WL) surveys will probe highly non-linear
scales with unmatched precision, providing valuable data for
improving cosmological parameter estimates. To accurately extract
non-Gaussian information from these data, higher-order statistics
were developed. However, their constraining power remains to be
tested. We examine the extent to which the scattering transform...

371. Constraining EFTofLSS countqerterms with Weak lensing

Despoina Farakou

Poster

We present constraints on Effective Field Theory of Large-Scale Structure (EFTofLSS) counterterms using weak gravitational lensing data and the Sym-EFT emulator [arXiv:2511.05093]. The emulator enables fast and accurate predictions for nonlinear matter power spectrum up to two loops. We study the sensitivity of weak lensing observables to EFT contributions and explore the constraining power of...

113. Constraining Inflation Models with Spinning Voids

GEONWOO KANG (Seoul National University)

Poster

We present a powerful new diagnostics by which the running of scalar spectral index of primordial density fluctuations can be tightly and independently constrained. This new diagnostics utilizes coherent rotation of void galaxies, which can be observed as redshift asymmetry in opposite sides dichotomized by the projected spin axes of hosting voids. Comparing the numerical results from the...

227. Constraining Late-Time Cosmology with DESI DR2

Prakhar Bansal (University of Michigan)

Dark Energy / Modified Gravity

Talk

In this talk, I present a set of complementary analyses aimed at constraining late-time cosmology with DESI DR2. I first discuss a model-independent reconstruction of the expansion history, where we directly constrain the background evolution without assuming a specific dark energy parametrization, finding results consistent with the standard $w_0$--$w_a$ framework; this work also includes the...

169. Constraining the growth rate of structure with DESI DR2 peculiar velocity survey

Yan Xiang Lai (University of Arizona)

Dark Energy / Modified Gravity

Talk

Recent results from the Dark Energy Spectroscopic Instrument (DESI) suggest that dark energy may evolve over time, potentially challenging the concordance cosmological model. An alternative explanation for dark energy is modified gravity, which predicts different growth rates for cosmic structures in the late universe. The DESI Peculiar Velocity (PV) survey is designed to systematically...

142. Constraining the lensing dispersion from the angular clustering of binary black hole mergers

Fumihiro Chuman (Chiba University)

Large-Scale Structure

Talk

Gravitational waves from inspiraling compact binaries provide direct measurements of luminosity distances and serve as a powerful probe of the high-redshift Universe. In addition to their role as standard sirens, they offer an opportunity to constrain small-scale density fluctuations through the dispersion in the distance-redshift relation induced by gravitational lensing. In this symposium,...

176. Constraints on Axion Dark Matter Isocurvature from CMB

Praniti Singh (Brown University (US))

Dark Matter

Talk

Measurements of the Cosmic Microwave Background (CMB) have confirmed a nearly scale-invariant primordial spectrum of adiabatic perturbations, in which the density fluctuations of radiation, baryons, and dark matter are in phase. However, primordial perturbations may also include an isocurvature component, in which the relative density fluctuations of individual species such as dark matter (DM)...

96. Cosmic Neutrino Background Detection with Tritium

Michiru Uwabo-Niibo

Neutrinos

Talk

The Cosmic Neutrino Background (CNB) is a robust thermal relic of the Big Bang and a potential probe of neutrino mass properties and of the Universe at O(1) second. A leading direct-detection strategy is neutrino capture on tritium, where observing a distinct capture peak requires excellent effective energy resolution. In practice, binding and solid-state effects can broaden the endpoint...

278. Cosmological analysis of cosmic shear and galaxy clustering with the KiDS survey

Christos Georgiou (IFAE)

Large-Scale Structure

Talk

Weak gravitational lensing has emerged as a competitive cosmological probe, and it is often combined with galaxy clustering to provide constrains on the matter density and matter fluctuations of the Universe. In this talk, I will present the cosmological analysis of data from the Kilo Degree Survey (KiDS), where we combine statistical measurements from galaxy shapes and galaxy positions using...

290. Cosmological Constraints on Novel Tsallis Holographic Dark Energy within Rastall Theory

Ms Behnoush Afshar (Research Institute for Astronomy and Astrophysics of Maragha)

Poster

In Rastall theory, the cosmological implications of new Tsallis holographic dark energy combined with the Rastall correction to General Relativity are investigated. A comprehensive data set—including Dark Energy Spectroscopic Instrument Baryon Acoustic Oscillations (Data Release 2), PantheonPlus Type Ia Supernovae, Hubble parameter measurements, and Big Bang Nucleosynthesis—is used to...

100. Cosmological first-order phase transitions with large bubbles: beyond conformal fluid and flat spacetime

Lorenzo Giombi (University of Helsinki)

Poster

Using semi-analytical models, we investigate the power spectrum of gravitational waves generated by sound waves in the plasma during a first-order phase transition in new unexplored scenarios. (i) The phase transition is accompanied by a change of the equation of state from that of pure radiation. This modifies the shape of the gravitational wave power spectrum as a consequence of both sound...

107. Cosmological gravitational particle production: Scalars and fermions

Duarte Miguel da Silva Feiteira (University of Helsinki)

Poster

In this talk, I will discuss the gravitational production of scalars and fermions during inflation. For scalars, I will compare Bogolyubov coefficient and Starobinsky stochastic approaches, showing that they only agree in the limit of infinitely long inflation. High-scale inflation is very efficient in particle production, leading to constraints on the existence of free, light, and stable...

146. Cosmological inference with halo clustering reconstructed from the redshift-space galaxy distribution

Ryuichiro Hada (Academia Sinica Institute of Astronomy and Astrophysics)

Large-Scale Structure

Talk

Accurate modeling of small-scale redshift-space clustering is crucial for full-shape RSD analyses, where satellite galaxies contribute to 1-halo terms and Finger-of-God distortions. We investigate halo reconstruction based on the cylinder grouping (CG) method of Okumura et al. (2017), which selects an effective halo center tracer from the observed galaxy distribution, and assess its impact on...

37. Cosmological Perturbations Induced by Ultralight Scalar Dark Matter: A Quantum Field Theoretic Perspective

Marco Vecchioni (Utrecht University)

Gravitational Waves

Talk

The growth of primordial perturbations during the matter-dominated era is primarily driven by dark matter. Ultralight scalar fields (ULDM) are a promising candidate for this role, conventionally modeled as operating in a classical, high-occupation regime. In this work, we develop a first-principles field-theoretic framework to investigate the impact of ULDM on linear cosmological perturbations...

170. Cosmological perturbations of a relativistic MOND theory

Hyerim Noh (Korea Astronomy and Space Science Institute)

Dark Energy / Modified Gravity

Talk

A relativistic MOND theory, promising reproducing cosmology as well as MOND phenomenology in the low accelerlation regime, was recently proposed. We present post Newtonian (PN) approximation and relativistic perturbation equations in cosmological context. The PN equations are presented to 1PN order and the perturbation equations are presented in fully nonlinear and exact forms. We show that...

186. Cosmological Perturbations with the Functional Renormalization Group

Juan Fernandez Molinero (Radboud University)

Inflation / Primordial Perturbations

Talk

Cosmological perturbation theory often serves as a tool to construct effective field theories (EFTs) for gravity and matter, describing a wide range of observed phenomena across different cosmological epochs. Within the asymptotic safety scenario for quantum gravity, the effective dynamics of quantum fluctuations around cosmological backgrounds can be derived from a UV-completion, offering a...

83. Cosmological Signatures of Photophilic Axions from Primordial Black Hole Domination

Sarunas Verner (University of Chicago)

Dark Matter

Talk

Light primordial black holes (PBHs) can briefly dominate the energy density of the early universe before evaporating via Hawking radiation, generically producing any sufficiently light degree of freedom in the process, including photophilic axion-like particles (ALPs). These ALPs subsequently decay to photons, injecting electromagnetic energy into the cosmic plasma at epochs ranging from BBN...

47. Cosmological tensions between CMB, BAO and SN

Wayne Hu

Cosmic Microwave Background

Talk

I will discuss tensions between CMB, BAO, SN distance measures and possible resolutions with optical depth, early dark energy, and axions.

163. Cosmology from the cross-correlation of CMB lensing from ACT-DR6 and galaxy shear from DES-Y3

Sunaina Desai (Cardiff University)

Large-Scale Structure

Talk

We cross-correlate measurements of lensing from two sources: the Cosmic Microwave Background (CMB) from the Atacama Cosmology Telescope (ACT)’s DR6, and galaxy shear from the Dark Energy Survey (DES) Y3. This presents the highest signal-to-noise measurement of its kind to date with a value of ~17.5, marking a significant improvement from the previous value of 7.1 made using ACT-DR4. This...

300. Cosmology from UNIONS Weak Lensing

Mike Hudson (Waterloo Centre for Astrophysics)

Large-Scale Structure

Talk

The Ultraviolet Near-Infrared Optical Northern Survey (UNIONS) is a 5-band ugriz imaging survey that will cover over 6000 square degrees of the northern sky, observed from telescopes in Hawaii. The imaging depth is similar to the Dark Energy Survey, but the sky coverage will ultimately be larger. Moreover, the northern sky has considerable overlap with redshift surveys such as the SDSS surveys...

152. Cosmology with ACT DR6

Hidde Jense (Cardiff University)

Cosmic Microwave Background

Talk

I present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, and the most recent constraints on cosmology from these, as measured from the Data Release 6 (DR6) of the Atacama Cosmology Telescope (ACT) data. ACT DR6 measures the CMB power spectra over a quarter of the sky in multiple bands in both temperature and polarization with arcminute...

177. Cosmology-informed constraints on the fuzzy dark matter mass from dwarf-spheroidal stellar kinematics

Shunichi Horigome (Tohoku University)

Dark Matter

Talk

Fuzzy dark matter (FDM) predicts a solitonic core within halos, in contrast to the cuspy inner profiles expected in the standard cold dark matter (CDM) model.
We investigate differences in the inner structure of dark matter halos through the stellar kinematics of dwarf spheroidal galaxies, which place constraints on the FDM particle mass.
We analyze the parameter space using a statistical...

213. Coupling the FIRE galaxy simulations to velocity dependent and anisotropic SIDM

Stephanie O'Neil (University of Pennsylvania, Princeton University)

Dark Matter

Talk

Understanding the interplay between dark matter physics and baryonic processes is critical for identifying the nature of dark matter. Self-interacting dark matter (SIDM), where dark matter particles can scatter with each other, is well motivated by theoretical models. Baryonic effects are often degenerate with dark matter physics, so a full picture is possible only through simulations that...

225. Cross-correlation between squared 21-cm field and patchy screening.

Hemanth Potluri (University of Groningen and Stellenbosch University)

Poster

The 21-cm signal from the Epoch of Reionization (EoR) traces the neutral hydrogen present in the IGM. The patchy ionization of neutral Hydrogen (HI) permeating Inter-galactic medium (IGM) makes the 21-cm signal highly non-Gaussian. The ionized bubbles, once formed, generate secondary anisotropies in the observed CMB signal. Patchy screening ($\tau_{es}$) is one such anisotropy that arises...

14. Dark Energy Survey Year-6 Pixel-to-Cosmology with Weak Lensing

Masaya Yamamoto

Dark Energy / Modified Gravity

Talk

The Dark Energy Survey (DES) provides a rich dataset to explore the effect of weak gravitational lensing on distant galaxies by the large-scale structure of the Universe. Weak lensing has become a powerful probe to investigate matter distribution in the Universe over the past decade thanks to large imaging surveys. In order to extract unbiased cosmological information from the dataset,...

362. Dark Matter and Stellar Dynamics Around Massive Black Holes

Barry Ginat (University of Oxford)

Gravitational Waves

Talk

In this talk, I will describe how to use stellar dynamics to constrain the distribution of dark matter around super-massive black holes, in two cases. First, concerning gravitational atoms of fuzzy dark matter (FDM) around black holes with nuclear stellar discs (like the Milky Way's): I will show that if the atom is in a spherically asymmetric state, there will be a differential torque on the...

368. Dark matter phase-in: Producing dark matter particles after a first-order phase transition

Felix Kahlhoefer (Karlsruhe Institute of Technology)

Dark Matter

Talk

If dark matter is produced non-thermally via non-renormalisable interactions (so-called UV-dominated freeze-in), the resulting abundance depends sensitively on the details of reheating. This sensitivity can however be much reduced in the presence of a cosmological first-order phase transition, after which the decaying scalar field transfers its energy density to the SM radiation, thereby...

275. Dark sector models with a vanishing speed of sound

Darío Jaramillo-Garrido (Universidad Complutense de Madrid and IPARCOS-UCM)

Dark Energy / Modified Gravity

Talk

We develop a field theory description of the dark sector, constructed under the requirement of having a vanishing fluid sound speed so as not to spoil cosmic structure formation. The form of the field theory naturally arises in transverse diffeomorphism invariant scenarios, in which case the dark sector is unified into a single scalar field. After a systematic model selection, we classify the...

342. De-lensing of CMB maps and constraining primordial gravitatinal waves: influence of Galactic foregrounds

Pawel Bielewicz (NCBJ)

Cosmic Microwave Background

Talk

Detecting primordial gravitational waves (PGWs) is one of of the main goal for upcoming Cosmic Microwave Background (CMB) experiments. Achieving this objective requires accurate removal of CMB gravitational lensing signal from CMB polarisation maps, so called de-lensing, as well as cleaning of the maps from diffuse Galactic foregrounds. In this talk I will present studies on influence of the...

120. Deconstructing the missing baryon environment with Fast Radio Bursts

Koustav Konar (University of Groningen and Stellenbosch University)

Large-Scale Structure

Talk

The precise distribution of baryons in the Universe remains an open question in cosmology, as their highly diffuse nature renders direct observation difficult, while being integral in achieving precise cosmological inference in studies of gravitational lensing, galaxy evolution and the cosmic microwave background radiation with the current and upcoming surveys. We use Fast Radio Bursts (FRBs)...

253. DES Y6: The Weak Lensing and Galaxy Clustering Analysis Framework

David Sanchez Cid (University of Zurich)

Methods / Statistical Inference / Machine Learning

Talk

The Dark Energy Survey Year 6 (DES Y6) represents the final and most statistically powerful dataset from DES, enabling sub-percent level cosmological constraints from weak lensing and galaxy clustering. We present the methodology underpinning the cosmic shear, 2×2pt, and 3×2pt analyses, focusing on the novel design choices that make this pipeline both robust and forward-looking. Key...

138. DESI results and time dependent Dark Energy from the QCD topological sectors

Prof. Ariel Zhitnitsky (University of British Columbia)

Dark Energy / Modified Gravity

Talk

We present a physically motivated dark-energy (DE) model rooted in the topological structure ofthe Quantum ChromoDynamic (QCD) vacuum. In this framework, which is coined as QCD-DE, the dark energy arises from the differencebetween the vacuum energy of an expanding FLRW universe and Minkowski spacetime, induced by tunnelling transitions between the QCD topological sectors. There are no any...

16. Detecting Relativistic Effects by Multi-tracing a Single Galaxy Population

Federico Montano (University of Turin)

Large-Scale Structure

Talk

Our well-established gravity model, the theory of general relativity, has been extensively tested in strong-field regimes. However, no observational test has yet confirmed its validity on cosmological scales, where the universe’s dark components are necessary to fit LSS data. The detection of large-scale relativistic effects via galaxy power spectrum measurements would provide such an...

85. Diffuse Polarised Synchrotron Reconstruction with GNILC on Latest Planck Data

Md Ishaque Khan (Instituto de Física de Cantabria (IFCA-CSIC-UC))

Cosmic Microwave Background

Talk

Primordial gravitational waves from inflation imprint a faint B-mode polarisation in the Cosmic Microwave Background (CMB), but this signal is strongly obscured by Galactic foregrounds. Detecting CMB B-modes therefore requires accurate characterisation of foreground polarisation, dominated by synchrotron emission at low frequencies. To address this, we apply the Generalised Needlet Internal...

209. Direct likelihood emulation for efficient cosmological parameter inference

Andreas Nygaard (University of Zurich)

Poster

Precision cosmology increasingly relies on repeated evaluations of computationally expensive observables, such as Cosmic Microwave Background (CMB) anisotropy spectra and large-scale structure statistics, posing a significant bottleneck for parameter inference and model comparison. Emulation techniques have emerged as a powerful solution, enabling fast and accurate interpolation of these...

73. Discovering Axion-like particles using CMB as a backlight.

Harsh Mehta (Tata Institute of Fundamental Research, Mumbai)

Dark Matter

Talk

Abstract: Axions or axion-like particles are hypothetical particles predicted by various BSM theories, which also make one of the dark matter candidates. The CMB is the primordial radiation that surrounds us and it follows an ideal blackbody spectrum, hence deviation in its behaviour can be used to probe new physics. If ALPs exist in nature, the CMB photons as they pass through galaxy...

194. Dissipation in Scalar-Tensor Cosmology

Adrián Casado-Turrión (Center for Physical Sciences and Technology (FTMC))

Poster

Physical processes (including field interactions and cosmological evolution) might have different interpretations in different conformal frames. In this talk, we shall discuss how to consistently transform dissipative phenomena between distinct conformal-frame representations of scalar-tensor gravity, and explore the observable consequences thereof in warm inflation scenarios, where the...

74. Distinguishing new physics via multi-messenger tests of the Distance Duality Relation

Matteo Martinelli (INAF - OAR)

Dark Energy / Modified Gravity

Talk

The Distance Duality Relation (DDR) is a cornerstone of the standard cosmological model, a direct consequence of basic assumptions such as photon conservation and the validity of null geodesics. Any detectable violation of this relation would provide a definitive signature of new physics, ranging from cosmic opacity and axion-like particles to modified theories of gravity. In this talk, I will...

232. Dynamical Dark Energy inspired by the QCD vacuum

Dong Ha Lee (University of Sheffield)

Poster

The nature of dark energy has been a growing point of debate in recent years, particularly after the DESI measurements of the Baryon Acoustic Oscillations. While frequentist metrics appear to indicate a growing preference for a dynamical dark energy, some bayesian approaches indicate otherwise. Beyond this, there also lies the question of whether there exists a physical motivation behind any...

124. Dynamical-State Dependence of the c–M Relation in Massive Dark Matter Halos

Mayuka Oda (University of Tsukuba)

Dark Matter

Talk

The concentration–mass (c–M) relation of dark matter halos is a key prediction of hierarchical structure formation and provides an important link between cosmological simulations and observations of dark matter halos. While the standard trend predicts a monotonic decrease of concentration with increasing halo mass, several studies have suggested a possible deviation from this behavior at the...

90. Echoes of Curvature: Cosmic Topology & Lens Spaces

Mikel Martin Barandiaran (Instituto de Física Teórica IFT UAM-CSIC)

Cosmic Microwave Background

Talk

The possibility of our Universe having a non-trivial spatial topology has received significant attention recently, as it could serve as a potential explanation of the Cosmic Microwave Background (CMB) large-angle anomalies and have interesting phenomenology in the early Universe. So far most efforts to study the shape of the cosmos have focused on spatially flat models, such as the simple...

110. Effect of Primordial Black Holes on the global 21-cm signal

Dr Atrideb Chatterjee (Kapteyn Astronomical Institute, University of Groningen)

Poster

The 21-cm global signal, a treasure trove of information about the nature of the first luminous sources of the Universe, has traditionally been modelled assuming that these early sources were predominantly star-forming galaxies. However, recent observations by the James Webb Space Telescope (JWST) have revealed several AGNs as early as z ~ 10 - 10.4 . In light of this, it is important to...

268. Effective field theory of in-in correlators

Guanhao Sun (Chongqing University)

Inflation / Primordial Perturbations

Talk

Equal-time in-in correlation functions are important observables for cosmological models and quantum field theories. In this talk, I will first explore how the Wilsonian renormalization group and effective field theory (EFT) apply to these observables in both flat and de Sitter space. Specifically, matching the UV and IR requires additional terms not captured by conventional EFT. These terms...

257. Effects of dark energy in structure formation

Priyanka Saha (Phd scholar, IIT Kanpur)

Poster

We present an extension of the spherical top-hat collapse model in a cosmological framework where the dark sector is composed of two interacting scalar fields. In this setup, one scalar field exhibits rapid oscillations on cosmological timescales and is interpreted as a viable dark matter candidate, while the second scalar field evolves smoothly and represents dark energy in the form of either...

331. Effects of Primordial Magnetic Fields (PMFs) in the linear and non-linear regimes

Anna D'Ambrosio (Scuola Internazionale Superiore di Studi Avanzati (SISSA))

Primordial Magnetic Fields

Talk

I am going to present how the presence of PMFs changes the shape of the matter power spectrum and how this results in new predictions for cosmological observables. By comparing theoretical predictions with observational data, it will be possible to constrain PMFs parameters. I will explore predictions from both the linear and non-linear regimes, such as the galaxy luminosity function and weak...

60. EFT approach to Dynamical Tides in Neutron star & Dark matter admixed Neutron Star

Soumodeep Mitra (University of South Dakota)

Poster

We apply the point particle EFT approach to a compact star to systematically compute dynamical tidal love numbers for various non-rotating compact objects. We calculate the scattering amplitude in Black Hole Perturbation Theory(BPHT) for arbitrary non-rotating compact stars using the Mano-Suzuki-Takasugi(MST) method with non zero surface reflectivity and match it with that obtained from point...

91. EFTofLSS and Newtonian Motion gauges

Julien Lesgourgues (RWTH Aachen university)

Large-Scale Structure

Talk

Using appropriate gauge transformations, one can extend the range of validity of standard perturbation theory or of the EFTofLSS. We show how to use Newtonian Motion gauges to compute accurately the one-loop matter power spectrum in redshift space taking into general relativistic effects, gravitational coupling with radiation, the scale-dependent growth induced by massive neutrinos and the...

349. Eigenmodes, correlation matrices, and detectability of Euclidean manifolds

Amirhossein Samandar (Case Western Reserve University)

Cosmic Microwave Background

Talk

If the Universe has non-trivial spatial topology, observables depend on both the parameters of the spatial manifold and the position and orientation of the observer. In infinite Euclidean space, most cosmological observables arise from the amplitudes of Fourier modes of primordial scalar curvature perturbations. Topological boundary conditions replace the full set of Fourier modes with...

332. Emulation of cosmological simulations using Evolution Mapping

Alejandro Pérez Fernández (Max Planck Institute for Extraterrestrial Physics)

Poster

With the advent of stage-IV spectroscopic galaxy surveys, modern cosmology has entered an era of unprecedented precision. While perturbation theory approaches remain the state of the art for large-scale structure (LSS) analyses, their applicability is restricted to the mildly non-linear regime, meaning that valuable data is being discarded. Simulation-based methods offer an alternative to push...

15. Enhanced foreground mitigation in thermal SZ Compton-y maps via polarization-aided cleaning and CIB deprojection

Jyothis Chandran (IFCA, Universidad de Cantabria)

Methods / Statistical Inference / Machine Learning

Talk

The thermal Sunyaev-Zeldovich effect Compton-y parameter map (y-map) is a redshift-independent tracer of the hot baryon density across the sky. The all-sky y-maps reconstructed from Planck data have been utilized for the study of Lambda-CDM cosmology and the astrophysics of galaxy clusters. The current best minimum variance, all-sky y-map was made public in our previous work, using Needlet ILC...

274. Enhancement of axion-density power spectrum via QCD phase transition

Jai-chan Hwang (IBS)

Early Universe

Talk

We present an enhancement of axion density power spectrum during the QCD phase transition. The axion-radiation coupling together with the self-interaction leads to an enhancement of the power spectrum on horizon scales during the phase transition. We evaluate the axion density power spectrum at the end of the QCD phase transition and show a pronounced enhancement for the hilltop initial conditions.

264. Equation of state during (p)reheating with trilinear interactions

Kenneth Marschall

Inflation / Primordial Perturbations

Talk

We study the post-inflationary evolution of the equation of state from the end of inflation to the onset of radiation domination. Focusing on single-field inflation models, we consider an inflaton field that has a quadratic potential near the minimum and is coupled to a massless scalar field via a trilinear interaction. The early preheating phase — dominated by resonance processes and...

319. Euclid Q1, Spitzer and ACT view on Planck galaxy protocluster candidates

Tanguy Dusserre (Institut d'Astrophysique Spatiale, Université Paris-Saclay)

Large-Scale Structure

Talk

As the largest and most massive gravitationally bound structures in the Universe, galaxy clusters stands at the crossroads between astrophysics and cosmology. Before they reach dynamical equilibrium, collapse and matter accretion from the cosmic web dictate their internal dynamics. Such objects are called protoclusters and are usually detected at $1.5<z<8$, way earlier than galaxy clusters...

291. Evaporating black holes: how the burden of their memory stabilizes them

Michael Zantedeschi

Early Universe

Talk

The memory burden effect describes how an object's stored information resists its own decay. This mechanism is especially pronounced in saturons - systems that saturate unitarity bounds on entropy - with black holes providing the prime example. I will show how memory burden can halt Hawking evaporation and dynamically stabilize black holes against complete decay. Crucially, this phenomenon is...

305. Excited states of wave dark matter halos after a sudden disturbance

Tejas Joshi (Institute of Physics, Polish Academy of Sciences)

Poster

We present an analysis of the nonequilibrium dynamics of a broad family of excited states of the Schrodinger Poisson equations. An initial spherically symmetric, groundstate soliton is stretched or squeezed and is let to freely evolve, thereby forming the soliton halo system. We investigate the mechanism of virialisation, including the observed scalar field bursts[1] and their connection to...

179. Exotic energy injection in the 21-cm power spectrum

Daniela Montes Doria (Australian National University)

Dark Matter

Talk

The 21-cm signal provides a new window into the thermal and ionization history of the early Universe, making it a powerful probe of exotic energy injection processes, including those sourced by dark matter (DM). We develop an effective parametric model for the heating deposition function, $f_{heat}(z)$, capturing the redshift-dependent impact of generic energy injection histories on the...

279. Exploring primordial signatures in Large-Scale Structure with GENGARS

Emanuele Fondi (Institut d'Astrophysique de Paris)

Poster

Primordial non-Gaussianity (PNG) provides a unique window into the nature of inflation, and large-scale structure (LSS) surveys offer a promising route to sharpen its constraints. While local PNG leaves a characteristic imprint on large-scale 2-point clustering statistics, many well-motivated non-local PNG models mainly induce higher-order correlations, making their signatures more difficult...

272. Extra Dimensions Revive Cosmic Strings in Pulsar Timing Arrays

Jun'ya Kume (University of Helsinki)

Early Universe

Talk

Cosmic strings are a well-motivated source of stochastic gravitational-wave backgrounds (SGWBs), but current pulsar timing array (PTA) data are often interpreted as favoring the supermassive black hole binary scenario over the standard Nambu–Goto string SGWB template. In this talk, I will show that this conclusion can change once cosmic strings are allowed to explore extra dimensions. The key...

180. Fast Neural Emulation of Cosmological Structure Formation with TUNeS

Yuqi Kang (Beijing Normal University)

Methods / Statistical Inference / Machine Learning

Talk

We present TUNeS (Temporal UNet emulator for Structure formation), a fast neural emulator for cosmological structure formation across redshift. Starting from the initial particle distribution, TUNeS predicts the evolved matter density field with a two-stage architecture that combines particle-based large-scale evolution and grid-based nonlinear refinement. The framework is designed to be...

266. Fermion (non)reheating in a quartic inflaton potential

Nabeen Bhusal (DESY)

Poster

Any viable inflationary model must account for reheating of the universe prior to the onset of primordial nucleosynthesis. In this work, we study the (p)reheating mechanism for an inflaton field with a quartic minimum of the T-model kind with coupling $\lambda$, prior to and post fragmentation, making a clear distinction between the two regimes. We assume that the main particle production...

298. Field-Level Baryonic Halo Painting for Weak Lensing

Max Lee (Columbia University)

Methods / Statistical Inference / Machine Learning

Talk

Baryonic feedback is one of the leading systematic uncertainties for upcoming Stage IV weak lensing surveys such as LSST, Euclid, and Roman. Standard baryon correction models offer a fast fix, but they are spherically symmetric by construction — missing the correlated, non-spherical structure of real baryonic fields and the galaxy shapes that drive intrinsic alignment signals.

I will...

269. Field-level vs summaries: convergence of information in non-Gaussian density fields

Ivana Nikolac (Max Planck Institute for Astrophysics)

Large-Scale Structure

Talk

Standard analyses of galaxy clustering rely on summary statistics such as the power spectrum and bispectrum, but extending to higher-order n-point functions quickly becomes intractable. Field-level inference (FLI) offers an alternative by forward-modeling the galaxy density field and explicitly employing the full joint posterior of the initial conditions, cosmological parameters, and bias...

67. First results of the LEGEND experiment in the quest for Neutrinoless Double-Beta Decay

Lucia Canonica (Università di Milano Bicocca)

Neutrinos

Talk

The search for neutrinoless double beta ($0\nu\beta\beta$) decay is considered as the most promising way to prove the Majorana nature of neutrinos as well as to give an indication on the mass hierarchy and on the absolute mass scale. The discovery of $0\nu\beta\beta$ decay would moreover open the way for theories predicting the observed matter--antimatter asymmetry of the Universe being a...

229. Forecast from a Lens-Equal-Source DES Year 6 3x2pt Analysis using Physics-Informed Priors

Zhengyangguang Gong (Steward Observatory, University of Arizona)

Large-Scale Structure

Talk

Current and next-generation wide-field surveys, such as the Dark Energy Survey (DES) and the upcoming Legacy Survey of Space and Time (LSST), will rely heavily on joint 3x2pt analyses, combining cosmic shear, galaxy-galaxy lensing, and galaxy clustering, to place stringent constraints on cosmological parameters. In this context, the selection and characterization of optimal galaxy samples is a...

366. Forward-Modelling Galaxy Surveys: A Robust Analytic Model for Projected Galaxy Bias

Maximilian von Wietersheim-Kramsta (Durham University)

Large-Scale Structure

Talk

Galaxies, as tracers of the large-scale structure of the Universe, are key observables for testing cosmological models in the late Universe and into the non-linear regime. In this context, multi-scale baryonic dynamics, and their evolution over time, can have considerable effects on the galaxy-halo connection. If unmodelled, residual uncertainties in the galaxy field can obstruct cosmological...

310. FOSSIL: A future mission for CMB spectral distortion measurements

Xavier Coulon (IAS-CNRS)

Cosmic Microwave Background

Talk

The only precise measurement of the cosmic microwave background (CMB) spectrum to date was achieved by COBE-FIRAS in the early 1990s, demonstrating that the CMB spectrum is extraordinarily close to a perfect blackbody emission. However, both standard and non-standard physical processes are expected to generate small deviations from this spectrum, known as CMB spectral distortions. These...

58. Freeze-In Production of Sterile Neutrino Dark Matter in a Low-Scale Seesaw Framework

SUHAIL KHAN (Centre for Theoretical Physics,Jamia Millia Islamia, New Delhi, India)

Dark Matter

Talk

In this work, we investigate the phenomenological aspects of a feebly interacting sterile neutrino dark matter candidate within a low-scale seesaw framework. The Type-I seesaw model is augmented by a second complex scalar doublet ($\Phi_{\nu}$), which couples exclusively to the heavy right-handed neutrinos and the lepton doublet, thereby generating the neutrino Dirac mass term while the first...

211. Freezing Gravity as a Model of Dark Energy Crossing the Phantom Divide

Zhibang Yao (Leiden University)

Dark Energy / Modified Gravity

Talk

Freezing Gravity is a recently proposed dark energy framework that enables a stable crossing of the phantom divide, motivated by current observational interest in dynamical dark energy. Its key feature is the independent control of the cosmological background and linear perturbations, which allows arbitrary background evolutions while maintaining freedom from ghost and gradient instabilities....

105. From astrophysics to cosmology with fast radio bursts

Robert Reischke (Argelander-Institut für Astronomie)

Large-Scale Structure

Talk

In recent years, Fast Radio Bursts (FRBs) have been established as a direct probe of baryonic matter. They are tracing the integrated ionised electron density along the line of sight through their observed dispersion measures. Upcoming radio surveys, such as the DSA, CHORD and the SKA, are expected to deliver up to 100,000 additional events. Their direct sensitivity to the Universe’s baryon...

252. From Cosmic Tensions to Fundamental Physics: A New Phase Transition in the Early Universe

Florian Niedermann

Early Universe

Talk

I will discuss how emerging observational tensions can be interpreted as signs of new dark-sector microphysics. In particular, I will present a model in which a symmetry-breaking phase transition reheats the dark sector after Big Bang nucleosynthesis, with dark matter coupled to dark radiation through a gauge force. This interaction generates dark acoustic oscillations on scales close to the...

248. From cutting rules to a minimal EFT for leptogenesis, dark matter, and neutrino masses

Dr Peter Matak (Comenius University (SK))

Poster

Using the CPT symmetry and unitarity as a starting point, we construct a minimal set of effective operators simultaneously accounting for the dark matter relic abundance and the matter-antimatter asymmetry of the Universe. Neutrino masses are generated via the Weinberg operator within a concrete realization of baryogenesis through leptogenesis. Remarkably, the Standard Model particle content...

311. From Few Simulations to Trustworthy Posteriors: Scattering-Covariance Latent Spaces for Simulation Augmentation and Interpretable SBI in CMB and Weak-Lensing Cosmology

Dr Paolo Campeti (Istituto Nazionale di Fisica Nucleare)

Cosmic Microwave Background

Talk

Modern CMB and large-scale-structure analyses face some of the same statistical bottleneck: the data are high-dimensional, non-Gaussian, affected by complex systematics, and often have intractable likelihoods, while the end-to-end simulations needed for Monte Carlo validation or Simulation-Based Inference are prohibitively expensive. I will present a unified framework based on the Scattering...

271. From flat space to de Sitter cosmological correlators

Nathan Belrhali

Poster

The generation of primordial density inhomogeneities from inflaton quantum fluctuations is a crucial prediction of inflation. The correlation functions of these fluctuations, called cosmological correlators, can be studied in a perturbative framework where the quantum fluctuations can be described as quantum fields that propagate in a de Sitter space-time. However, this propagation has a...

95. From Primordial Gravitational Waves to Large-Scale Structure: Induced Density Perturbations and Their Signatures

Pritha Bari (Institute for Basic Science CTPU-CGA)

Large-Scale Structure

Talk

Primordial gravitational waves (GWs) can source scalar density perturbations at second order, thereby leaving indirect but potentially observable signatures in the large-scale structure (LSS) of the Universe. In this talk, I will present a comprehensive study of these tensor-induced density perturbations, from their analytic evolution in the radiation- and matter-dominated eras to their...

65. From Simulations to Early Data: Galaxy Cluster Cosmology with LSST-DESC

Eduardo Barro (LAPP)

Poster

In this work, we present recent developments and forecasts related to galaxy cluster science within the LSST-Dark Energy Science Collaboration (DESC). Galaxy clusters are among the primary cosmological probes of LSST. However, their use for precision cosmology is challenging as it requires the construction of cluster catalogs from observations and accurate modeling to extract cosmological...

335. From the Wavefunction of the Universe to In-In-Correlators: A Perturbative Map to All Orders

Gonzalo Palma (FCFM, University of Chile)

Inflation / Primordial Perturbations

Talk

Both the Wavefunction of the Universe and the Schwinger-Keldysh in-in formalism are central tools for analyzing primordial cosmological observables, such as equal-time correlation functions. While their conceptual equivalence is well established, a systematic and explicit map between their diagrammatic expansions has remained elusive. In this talk, I show how to construct such a map by...

219. Fundamental Physics at small scales with Hydrogen

Matteo Viel (SISSA)

Primordial Magnetic Fields

Talk

I will discuss how atomic hydrogen in absorption and emission can be used to address fundamental physical questions by probing non-linear scales. I will focus on the following topics: primordial magnetic fields and their impact on structure formation, dark matter nature. I will also briefly address what is the advantage of using atomic hydrogen to perform field level inference in the...

89. Galaxy clustering on the full sky

Greg Lukens (Pennsylvania State University)

Dark Energy / Modified Gravity

Talk

The newest generation of galaxy surveys are ushering in an era of precision large-scale structure cosmology, making a rigorous full-sky treatment of galaxy clustering useful and essential. In this talk, I present a framework for computing the angular power spectrum of galaxies on the full sky which incorporates all linear order relativistic effects that become significant on ultra-large...

165. Galileons in curved spacetime and numerical challenges

Mary Gerhardinger (University of Pennsylvania)

Dark Energy / Modified Gravity

Talk

The Galileon theory provides an infrared modification of general relativity that incorporates the Vainshtein screening mechanism, suppressing deviations from general relativity on local scales. In this talk, I examine analytic solutions of the Galileon field in curved spacetimes. In a de Sitter background, an additional scale emerges at which the scalar field becomes singular, signaling the...

317. Gauge Fields and Their Uses During Inflation

Prof. Matteo Fasiello (IFT Madrid)

Inflation / Primordial Perturbations

Talk

I will discuss the role of gauge fields during inflation, with particular emphasis on scenarios where they are coupled to an axion-like inflaton. Such couplings can lead to rich dynamics with observable consequences, including the production of chiral primordial gravitational waves and primordial black holes. In addition, gauge fields can play an important role in reheating and provide a...

341. Generic features of the evolution of scalar field dark matter galaxy halos

Piotr Deuar (Institute of Physics, Polish Academy of Sciences)

Poster

We study the nonlinear evolution of scalar field dark matter galaxy halos that undergo a broad family of sudden disturbances created by a stretching or compression of the ground state, or spontaneous collapse from an almost uniform background. To date we have worked in reduced dimensions (spherical symmetry, plus exploratory attempts in cylindrical geometry for consideration of dark matter...

284. Geometric Z': Dark Matter, and Black Hole Probes

Beyhan Puliçe (Istinye University)

Dark Matter

Talk

In this talk, I will discuss a purely geometric vector field arising in metric-Palatini gravity and its interpretation as a possible fifth force. When metric-Palatini gravity is extended by the antisymmetric part of the affine Ricci tensor together with a matter sector involving the affine connection, the theory dynamically reduces to general relativity together with a massive vector field of...

5. GPU-accelerating CMB cosmology with state of the art ODE solvers

Lawrence Berry (Institute of Astronomy, University of Cambridge)

Methods / Statistical Inference / Machine Learning

Talk

GPUs offer a way to massively parallelise certain types of physical models, allowing us to compare more models for the same compute budget (and hence do more science) whilst avoiding the use of emulators (which must be retrained every time you modify the underlying physics). More efficient forward models also allow us to tackle higher-dimensional problems (such as in field-level inference) and...

133. Gravitational Particle Production in Multifield Inflation Models

Edward Kolb (University of Chicago)

Early Universe

Talk

There are subtleties associated with cosmological gravitational particle production in inflation models with more than one dynamical field. In the presentation I will discuss the formalism and provide some examples.

118. Gravitational Properties of the Monopole Bag

Yu Komiya (Yukawa Institute for Theoretical Physics, Kyoto University)

Early Universe

Talk

Axionic cosmologies constitute a class of models offering a well-studied candidate for dark matter (the axion) as well as phenomenologically rich symmetry breaking in the early universe. In the case where monopoles are present in such a background, the axion profile may be deformed; it is possible to construct a "monopole bag" state composed of a central monopole within a closed axion domain...

132. Gravitational Wave Signatures of $U(1)_X$ Breaking and Right-Handed Neutrino Dynamics

Dr Rukmani Mohanta

Poster

Though the Standard Model of particle physics is incredibly successful, but it leaves several fundamental questions unanswered, including the origin of neutrino masses, the baryon asymmetry of the Universe, and the nature of dark matter. Motivated by these gaps, we investigate an extension of the SM with an additional local $U(1)_X$ gauge symmetry and a complex scalar singlet that...

196. Gravitational Waves from a Dilaton-Induced, First-Order QCD Phase Transition

Charalampos Nikolis

Gravitational Waves

Talk

We show that a QCD dilaton field, whose vacuum expectation value sets the strong coupling, can render the quantum chromodynamic (QCD) confinement transition first order. The QCD dilaton is cosmologically attracted to a false vacuum at weak coupling in the early Universe. Quantum tunneling toward the true vacuum triggers prompt chiral symmetry breaking and confinement of QCD, leading to...

285. Gravitational Waves from Cosmic Strings with Backreaction

Lasse Gerblich (University of Cambridge)

Poster

Cosmic strings are one-dimensional topological defects, which are formed during symmetry-breaking phase transitions with a non-simply connected vacuum manifold. If they exist, they are expected to generate gravitational waves, which we might be able to detect with future gravitational wave observatories such as LISA or Einstein Telescope. In particular, local features on the strings, such as...

11. Gravitational waves from cosmic textures

Takashi Hiramatsu (Nihon University)

Early Universe

Talk

Cosmic textures are non-trivial field configurations arising from spontaneous symmetry-breaking, $G\to H$, for which $\pi_3(G/H)$ is nontrivial. Global textures are known to be sources of gravitational waves in the literature, whereas gauged textures have not been well studied, since some of them are pure gauge. In the present study, we focus on gauged SU(2) and O(4) textures, following the...

350. Gravitational Waves from Primordial Black Hole Binaries: The Role of Higher-Order Clustering

Changcheng Jing (Instituto de Física Teórica UAM-CSIC)

Gravitational Waves

Talk

Primordial black holes (PBHs) formed in the early Universe are a well-motivated dark matter candidate and a potential source of gravitational waves (GWs). In this work, we investigate the GW signals originating from early-formed PBH binaries, with a particular focus on the impact of primordial clustering induced by non-Gaussianity in the curvature perturbations. We model the spatial...

39. Gravitational-Wave Propagation Through the Axiverse

Leah Jenks (Johns Hopkins University)

Gravitational Waves

Talk

In this talk I will discuss how oscillating ultralight scalar and pseudoscalar fields affect the propagation of gravitational waves (GWs). I will consider two couplings of the (pseudo)scalars to gravity; a parity-even Gauss-Bonnet coupling, and parity-odd Chern-Simons coupling, and show that these fields induce distinctive signatures at both the population and individual GW event levels. These...

40. Gravity’s Gift: Baryons from the Big Bang

Andrew Long (Rice University)

Early Universe

Talk

This talk is based on a recent paper in which my collaborators and I have explored how the cosmological excess of matter over antimatter can arise through the phenomenon of cosmological gravitational particle production at the end of inflation in a Type-I Seesaw model of nonthermal leptogenesis. From a model-building standpoint, this scenario is appealing for being minimal and economical,...

61. GW probe of EMRIs in Scalar field Dark matter spike

Soumodeep Mitra (University of South Dakota)

Gravitational Waves

Talk

Scalar field dark matter (SFDM) is an exciting and attractive alternative dark matter model which can successfully alleviate various issues plaguing traditional cold dark matter models. However, detecting SFDM is no easy task, as it may or may not interact with standard model particles
at all- making terrestrial experiments moot. On the other hand, dark matter distribution near the galactic...

80. Halo structure and lensing signatures of a polytropic dark matter fluid

Marriam Naeem

Dark Matter

Talk

We investigate whether a minimal effective pressure in the dark matter sector can generate observable deviations from standard cold dark matter ($\Lambda$CDM) predictions at nonlinear scales. We model dark matter as a polytropic fluid with equation of state $P = K \rho^{3/2}$, interpreted as an effective coarse-grained closure of the collisionless Jeans hierarchy in virialized halos.

For...

78. Healthy scalar-tensor theories with third-order derivatives: Cosmological perturbations

Tsutomu Kobayashi (Rikkyo University)

Dark Energy / Modified Gravity

Talk

I describe how one can systematically construct covariant, ghost-free scalar-tensor theories whose Lagrangian includes up to third-order derivatives of the scalar field. The resultant theories extend the generalized disformal Horndeski and U-DHOST theories. I then discuss cosmological perturbations, emphasizing the role of new terms on EFT of Dark Energy.

365. HETDEX [OII] galaxies at z < 0.48 : Volume-limited samples and their power spectra

Jeongin Moon (Max-Planck Institute for Astrophysics)

Large-Scale Structure

Talk

The Hobby-Eberly Telescope Dark Energy Experiment(HETDEX) delivers an unprecedented catalog of over two million emission-line-selected galaxies through its untargeted IFU spectroscopic survey using the VIRUS spectrograph on the 10m HET. The first public data release(PDR1) includes approximately half a million [OII] emitters at z≤0.48, providing a unique and complementary probe of large-scale...

137. Hidden Gravitons: From Dark Matter Candidates to Gravitational Wave Oscillations

Prof. Jose Cembranos

Gravitational Waves

Talk

Massive spin-2 fields naturally arise in various extensions of General Relativity, including massive bigravity and Kaluza-Klein models. This presentation explores the observational signatures of these hidden gravitons that can work as dark matter. In particular, we pay attention to the phenomenology associated with the propagation of gravitational waves. Within a phenomenological framework, we...

34. Higgs mass and wino dark matter in Starobinsky supergravity coupled to the MSSM

Daniel Frolovsky (Institute for Theoretical Physics, Utrecht University,)

Poster

A framework connecting Cosmic Microwave Background (CMB) observables with high-energy particle phenomenology is proposed, which is based on Starobinsky supergravity coupled to the Minimal Supersymmetric Standard Model (MSSM). In this approach, the amplitude of primordial perturbations during inflation fixes the vacuum expectation values (VEVs) of scalar fields in the hidden sector arising from...

119. Higgs-portal dark matter beyond kinetic equilibrium

Michele Benaco (University of Jyväskylä)

Dark Matter

Talk

Higgs portal models are among the simplest and most widely studied realizations of particle Dark Matter (DM). We revisit scalar, vector, and fermionic Higgs portal models, focusing on the resonant regime and dropping the assumption of kinetic equilibrium. We solve for the full momentum-dependent Boltzmann equations using the DRAKE code and compare the outcomes with the Lee-Weinberg solution...

326. Higher-order Galaxy Bias: Theory and Numerics

Thomas Bakx (Utrecht University)

Poster

The large-scale distribution of galaxies encodes cosmological information on the history and matter content of the Universe. The full, non-Gaussian galaxy distribution can be analysed on large scales using a perturbative formulation of galaxy bias, which is the effective field theory of large-scale structure. State-of-the art full-shape analyses of past surveys such as BOSS and currently...

307. How Galaxy Formation Physics Impacts Primordial Non-Gaussianity Constraints in DESI

Miguel de Icaza (Universidad Autónoma de Madrid)

Large-Scale Structure

Talk

Primordial non-Gaussianities (PNG), parameterized by the amplitude fNL​, provide a direct window into the physics of the early Universe and a means to discriminate among inflationary models. Constraints on fNL​ from the cosmic microwave background are limited by cosmic variance, making large-scale structure surveys such as DESI a promising avenue for further progress. A central challenge is...

79. How galaxy properties and evolution shapes their intrinsic alignments in hydrodynamical simulations

Marloes van Heukelum (Utrecht University)

Large-Scale Structure

Talk

Galaxies that are spatially correlated, also show position-shape correlations of their major axes. This correlation, called intrinsic alignment, is a major contaminant in cosmological analyses of weak lensing surveys and therefore needs to be modelled well and understood. While intrinsic alignment correlations have been established and modelled quite well for linear scales for large central...

29. Hubble constant dipoles and bulk flows with eROSITA galaxy clusters

Konstantinos Migkas (Leiden University)

Large-Scale Structure

Talk

The isotropy of cosmic expansion and the dissipation of bulk flows on large scales are fundamental assumptions of the $\Lambda$CDM paradigm. However, evidence from independent cosmological probes for large-scale cosmic dipoles and anomalous bulk flows continues to mount. These emerging tensions, therefore, require careful and independent scrutiny.

Galaxy clusters constitute powerful and...

117. Hunting Sterile Neutrino Dark Matter in the MeV Gap

Dr Shivam Gola (IIT Bombay)

Neutrinos

Talk

We investigate the sensitivities of upcoming MeV gamma-ray telescopes to sterile neutrino dark matter in the mass range (0.2−100)MeV. Sterile neutrinos in this regime can produce observable photon signals through radiative two-body decays and three-body decays with final-state radiation. We perform a Fisher forecasting analysis incorporating realistic astrophysical background modeling and...

178. Identification of structures in the Universe through quasar clustering

Diana Carolina Zapata Zuluaga (Universidad de Antioquia)

Poster

Quasars are powerful tracers of the large-scale structure of the Universe at redshifts where dense galaxy samples are harder to obtain. In this work, we use the Quaia quasar catalog, considering the G<20.5 and G<20.0 magnitude-limited samples, to reconstruct and characterize the cosmic web traced by quasars. After applying a sigma-clipping selection in the $(z, z_{\mathrm{error}}/z)$ plane, we...

149. Identification of Wave-optics Lensed Gravitational Waves with Residual Cross-correlation from GWTC-4 events

Aniruddha Chakraborty (TIFR Mumbai)

Gravitational Waves

Talk

The lensing of Gravitational Waves (GWs) due to intervening matter distribution in the universe can lead to chromatic signatures in the wave-optics limit. The reliance of the lens mass distribution modelling makes detection of lensed GWs challenging. Hence to detect lensed GWs in a model-independent way, we develop the wave-optics lensing search technique called mu-GLANCE and deploy it on the...

187. Impact of Teleparallelism on Addressing Current Cosmological Tensions

Prof. Pradyumn Kumar Sahoo (Birla Institute of Technology and Science-Pilani, Hyderabad Campus)

Poster

The ( H_0 ) and ( S_8 ) tensions pose significant challenges to the standard ( \Lambda )CDM model, arising from discrepancies in local versus early-Universe ( H_0 ) measurements and inconsistencies between CMB and weak lensing data. We explore two ( f(T) ) gravity models as alternatives by analyzing cosmic chronometers, BAO, gamma-ray bursts, and Pantheon+SH0ES datasets, with...

263. Imprints of helical primordial magnetic fields on parity-violating cosmological statistics

Kaito Yura (Nagoya University)

Primordial Magnetic Fields

Talk

Primordial magnetic fields are well motivated by the observations of the cosmic magnetic fields on various scales and have been attracting attention as a possible origin of the large-scale magnetism in the Universe. Several studies have also suggested that intergalactic magnetic fields may possess helicity, corresponding to an asymmetry between the right- and left-handed components. Since...

297. Improved cosmological constraints on axion-lepton interactions

Adam Gomułka (University of Warsaw, Faculty of Physics)

Early Universe

Talk

We investigate lepton-flavour-conserving (LFC) and lepton-flavour-violating (LFV) axion-lepton couplings using cosmological data, addressing the specific mass ranges where the standard $\Delta N_\mathrm{eff}$ approximation fails. We implement a full phase-space treatment of thermal axion production and incorporate finite axion mass effects to test these couplings against Planck 2018 CMB and...

359. Improving Constraints on Inflation with the South Pole Observatory

Scott Mackey (University of Chicago)

Cosmic Microwave Background

Talk

Cosmic inflationary models predict a background of primordial gravitational waves that would imprint a B-mode polarization signature in the cosmic microwave background (CMB). The South Pole Observatory (SPO), a joint effort between BICEP and the South Pole Telescope (SPT), aims to constrain the strength of this signature, parameterized by the tensor-to-scalar ratio r, and thereby constrain the...

357. Improving the Precision of BICEP’s CMB Measurements

John Kovac (Harvard University)

Cosmic Microwave Background

Talk

For over 20 years, the BICEP series of telescopes has been observing CMB polarization from the South Pole with ever increasing sensitivity, continually improving the leading constraints on primordial gravitational waves and the faint B-modes they would produce at degree scales. The measurement challenge is immense. As sensitivities continue to increase, from existing datasets which constrain...

339. In Search of New Physics in the CMB Using AI

Andrius Tamosiunas (University of Oslo)

Methods / Statistical Inference / Machine Learning

Talk

In this talk, I will present a set of AI techniques designed to look for signatures of new physics in CMB data. In particular, I will introduce how spherical graph neural networks can be applied to perform machine learning directly on CMB temperature and polarization map data. Furthermore, I will discuss how recent advances in agentic AI can assist with a variety of tasks ranging from...

216. Inconsistencies of Tsallis cosmology within horizon thermodynamics and holographic scenarios

Mr PEDRO MARTIN IBARBO PERLAZA (Universidad del Valle)

Poster

We investigate the cosmological implications of Tsallis entropy in two widely discussed frameworks: the Cai–Kim thermodynamic derivation of the Friedmann equations and the Tsallis holographic dark energy (HDE) scenario, considering both the Hubble scale and the Granda–Oliveros (GO) cutoff as infrared regulators. In both cases, the dynamics introduce a nonextensivity parameter $\delta$, with...

115. Inflation beyond perturbation theory

Mr Sébastien Renaux-Petel (CNRS-IAP)

Inflation / Primordial Perturbations

Talk

The wavefunction of the universe contains the full information about primordial fluctuations. I will show how to determine it in a non-perturbative manner in a large class of inflationary scenarios, using the exemple of models with small and rapid oscillations in the inflaton potential. Our study reveals a profound asymmetry between maxima and minima of the density fluctuations, and indicates...

258. Inflation from Pure Geometry: Precision Cosmology in R+R²−W² Gravity

Mauricio Gamonal (Penn State)

Poster

Starobinsky's $R+\alpha R^2$ model provides a compelling description of cosmic inflation, and its observational support has established it as a benchmark for model comparison. However, at the same order in the local curvature expansion, an effective theory of spacetime geometry naturally includes the Weyl-squared invariant $W^2$, making $R+\alpha R^2−\beta W^2$ the minimal purely gravitational...

348. Integral-Equation Method for Non-Cold Relic Perturbations: From Massive Neutrinos to Decaying Dark Matter

Nanoom Lee (Johns Hopkins University)

Neutrinos

Talk

The standard approach for computing perturbations of non-cold relics in Boltzmann solvers relies on a truncated multipole hierarchy, which introduces numerical artifacts and becomes computationally expensive at small scales. We present an alternative framework based on integral equations (IEs), where the formal solution to the collisionless Boltzmann equation is expressed as a convolution of...

308. Integrated effects in Large Scale Structure

Jessie Hammond (Queen Mary, University of London)

Large-Scale Structure

Talk

Measuring primordial non-Gaussianity (PNG) is one of the goals of current and future galaxy surveys. Since general relativistic effects are degenerate with any signal measured from PNG, a fully relativistic, non-Newtonian approach is required. In previous studies, integrated line-of-sight effects, such as lensing convergence, Shapiro time delay and integrated Sachs-Wolfe, have largely been...

31. Interpretable machine learning for dynamical dark energy models

Giulia Borghetto (University of Swansea)

Poster

Recent cosmological observations suggest possible deviations from a cosmological constant, pointing toward a dynamical nature of dark energy. Quintessence models, which assume a slowly rolling scalar field, provide a compelling theoretical framework to explain this late time evolution in the dark energy equation of state. However, identifying the correct form of the quintessence potential...

75. Intrinsic alignments in the FLAMINGO simulations and consequences for weak lensing

Aniruddh Herle (Leiden Observatory)

Large-Scale Structure

Talk

Weak gravitational lensing has emerged as one of the most powerful probes of cosmology, uniquely tracing the total matter distribution and directly probing the growth of large-scale structure. As a late-time observable, it provides key sensitivity to dark energy that complements early-Universe measurements of the Cosmic Microwave Background. Forthcoming surveys such as $\textit{Euclid}$ and...

286. Intrinsic Galaxy Shapes as a Novel Probe of Cosmology: Primordial Parity Violation with Intrinsic Alignments

Toshiki Kurita (Max Planck Institute for Astrophysics)

Large-Scale Structure

Talk

Intrinsic alignment (IA), the large-scale correlation of intrinsic galaxy and halo shapes, is recognized not only as a major systematic in weak-lensing analyses but also as a cosmological signal in its own right. Because IA is sensitive to the gravitational tidal field and its higher-order statistics, it provides information complementary to standard late-time observables and may open a new...

201. Introducing the Self-Interacting Dark Matter Galaxy Cluster Simulations from The Three Hundred Project

Ellen Sirks (Universidad Autónoma de Madrid)

Dark Matter

Talk

Dark matter constitutes the majority of the matter content of the Universe, yet its fundamental properties remain unknown. Its presence is inferred through its gravitational effects on cosmic structures across all scales. Galaxy clusters, which are the most massive gravitationally bound systems in the Universe, are particularly powerful environments for probing the nature of dark matter due to...

147. Is Gaussian good enough? Likelihoods for cosmological two-point functions

Veronika Oehl

Methods / Statistical Inference / Machine Learning

Talk

Two-point correlation functions are a standard tool in cosmology. However, their estimators have intrinsically non-Gaussian likelihoods, even for perfectly Gaussian random fields. This non-Gaussianity is most evident on the large scales targeted by stage-IV weak lensing surveys. We present a framework for computing exact correlation-function likelihoods for the masked spin-2 fields of cosmic...

306. KiDS Legacy cosmic shear analysis with the KiDS MetaCalibration pipeline

Mijin Yoon (Leiden Observatory)

Large-Scale Structure

Talk

We developed a new shear measurement pipeline in the Kilo-Degree Survey (KiDS) collaboration, MetaCalibration, which is robust as it is less sensitive to the morphology of observed galaxies. In the KiDS-1000 cosmic shear analysis, the MetaCalibration pipeline increased 28 percent constraining power on the cosmological parameter ($S_8$) compared to the fiducial pipeline, lensfit, because of the...

249. Kontorovich-Lebedev-Fourier Space for de Sitter Correlators

Arthur Poisson (Institut d'Astrophysique de Paris)

Poster

The study of late time correlation functions on top of a de Sitter
background is of prime interest in primordial cosmology.
Due to the non-conservation of energy, their evaluation represent a
significant technical challenge and their mathematical structure remains
unclear. In this talk, I will propose a new
direction to address both of these issues by introducing a
frequency-momentum...

356. Large deviation techniques for structure abundances : beyond perturbative non-gaussianities

Martin Teuscher (LPSC Grenoble, France)

Poster

The excursion-set formalism provides a key connection between primordial inflationary fluctuations and the abundance of cosmic structures such as dark matter halos and voids, traditionally assuming Gaussian random walks. In this work, we extend this framework to fluctuations whose distribution present strongly non-Gaussian tails, beyond the reach of perturbative approaches to primordial...

282. Large Primordial Fluctuations: Stochastic vs. Classical $\delta N$ approaches

Parth Bhargava (ICG, Portsmouth)

Inflation / Primordial Perturbations

Talk

The classical evolution of fields during a period of accelerated expansion in the very early universe ("inflation") can establish an idealised homogeneous and isotropic cosmology. However, quantum fluctuations inevitably generate inhomogeneities and anisotropies on all observable scales and beyond. The $\delta N$ formalism provides a powerful framework to describe the nonlinear curvature...

125. Latest CRESST results on sub-GeV dark matter and the low-energy excess challenge

Danae Danielle Valdenaire (Austrian Academy of Sciences (AT))

Poster

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) is a direct detection dark matter experiment located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy.

The experiment searches for dark matter–nucleus interactions using scintillating cryogenic calorimeters equipped with transition edge sensors (TESs), which measure phonon signals at millikelvin temperatures,...

128. Latest results from the South Pole Telescope

Lennart Balkenhol

Cosmic Microwave Background

Talk

The South Pole Telescope is a dedicated 10-meter cosmic microwave background (CMB) telescope at the Amundsen-Scott station in Antarctica, and its current receiver, SPT-3G, equipped with 16,000 detectors in three millimeter-wave bands, has been used to map large areas of the sky since 2017. The combination of large primary mirror and high detector count allows us to produce high-resolution,...

281. Lattice Simulations of Multifield Inflation

Lena Janssen (University of Groningen)

Inflation / Primordial Perturbations

Talk

The inflationary period in the early universe provides a widely accepted mechanism for generating primordial perturbations. While some single-field models successfully reproduce current observations, multifield models can lead to distinct observational signatures on scales much smaller than those probed by the cosmic microwave background. Multifield models of inflation introduce richer...

345. Learning CMB-independent reionisation constraints from high-redshift quasars

Timo Kist (Leiden Observatory)

Methods / Statistical Inference / Machine Learning

Talk

Recent evidence for evolving dark energy from DESI BAO measurements has been shown to be degenerate with the optical depth to reionisation tau_CMB and could be absorbed in a value exceeding Planck's legacy measurement of tau_CMB ~ 0.05. Gaining a true understanding of the Epoch of Reionisation therefore remains one of the pivotal tasks of modern cosmology, and next-generation telescopes such...

220. Light Particles in the Halo Bias

Nicholas DePorzio (Boston University)

Large-Scale Structure

Talk

In this talk I will introduce the key cosmological datasets — the cosmic
microwave background and galaxy surveys — and explain how they serve as particle
detectors for the lightest particles in nature. I will describe the vast landscape of
dark matter candidates, spanning many orders of magnitude in mass, and show how
cosmological observables can distinguish among them. A central theme of...

247. Light scalar fields on a curved background and their influence on the dynamics of galaxies.

Lukasz Bunio (University of Manchester)

Dark Energy / Modified Gravity

Talk

We consider two extended theories of gravity involving non-minimally coupled scalar fields and investigate their influence on galactic scales. To do so, we linearise the equations of motion for the scalar fields, accounting for their dependence on curvature scalars. In this way, we recover known results and are able to extract the modifications over Einstein gravity due to the presence of the...

104. LISA Can Detect Dark Matter Subhalos through Gravitational-Wave Lensing

Shin'ichiro Ando (University of Amsterdam)

Dark Matter

Talk

Strongly lensed gravitational waves offer a new way to study dark matter structure on subgalactic scales. In the wave-optics regime, gravitational waves propagating through a population of dark matter subhalos acquire frequency-dependent amplitude and phase distortions that encode the small-scale matter distribution along the line of sight.

We compute the full diffraction integral for...

283. Localized Detection of Baryon Acoustic Oscillation Shells in DESI DR1

Edward Olex (Universidad Autónoma de Madrid (Spain))

Large-Scale Structure

Talk

I present results from a new local approach to detecting and characterizing Baryon Acoustic Oscillations (BAO) in the large-scale distribution of matter. The possibility of observing individual BAO structures in configuration space was long speculative until the Hoʻoleilana candidate (Tully et al. 2023), discovered in the Cosmicflows-4 dataset, revealed a single shell-like over-density with...

292. Lukewarm inflation, primordial black holes, gravitational waves and the GUT scale QCD axion

António Manso (Jozef Stefan Institut)

Poster

In this talk we present "Lukewarm Inflation", a concrete particle physics model with parametrically low reheating temperatures that can naturally generate a parametrically large, broad, nearly-flat enhancement of the primordial curvature power spectrum. In the case of reheating temperatures $T_R\sim5$ TeV, this simultaneously produces planet-mass primordial black holes and scalar-induced...

323. Magnetic monopole plasma oscillations and implications for TeV Blazars

Mariia Khelashvili (SISSA)

Primordial Magnetic Fields

Talk

Magnetic monopoles arise in many beyond Standard Model scenarios, symmetrize Maxwell's equations, and explain the quantization of electric charge. It has been argued that, when placed in an astrophysical magnetic field, monopoles induce a magnetic version of plasma oscillations. In this work, we explore monopole-induced oscillations of the intergalactic magnetic field (IGMF). We show that...

87. Measuring clustering using k-Nearest Neighbour Statistics

Kwanit Gangopadhyay (University of Groningen)

Poster

The matter field in the universe is a Gaussian Random Field on large scales and early times, summarized by the power spectrum or two-point correlation function. However, on smaller scales and late times, non-linear gravitational evolution results in non-Gaussian clustering, necessitating improved summary statistics. k-Nearest Neighbour Cumulative Distribution Functions ($k$NN CDFs) are...

6. Measuring cosmic bulk flow with kinetic Sunyaev-Zel'dovich (kSZ) velocity reconstruction

Suroor Seher Gandhi (Perimeter Institute for Theoretical Physics)

Large-Scale Structure

Talk

The average large-scale velocity of matter in the universe, known as cosmic bulk flow, is a fundamental test of the Cosmological Principle. Traditionally, this has been measured only out to $R\lesssim 100$ megaparsecs (Mpc). We present an application of kinetic Sunyaev-Zel'dovich (kSZ) velocity reconstruction to constrain bulk flow on cosmological scales more than $10\times$ larger,...

280. Measuring magnetic fields at cosmological distances with gravitational lensing

Willem de Roo (Max Planck Institute for Astrophysics)

Primordial Magnetic Fields

Talk

Magnetic fields drive galaxy evolution by shaping the interstellar medium and regulating star formation. However, their origins and cosmic history remain obscure. To understand the evolution of magnetic fields from initial seed fields to well-ordered systems, resolving the spatial structure of these fields across cosmic time is essential. Although achievable in local galaxies, this task...

287. Measuring scalar tensor dynamics in the early universe

Keyi Ding

Primordial Magnetic Fields

Talk

Current searches for non-Gaussianity are mostly limited to higher-order correction functions of scalar perturbations. In the meantime, primordial B-mode detection is one of the main goals of next-generation CMB experiments. Bispectra involving B-modes, i.e., $\langle TTB \rangle, \langle EEB \rangle$, and $\langle TEB \rangle$ are of great importance for two reasons:
First, tensor...

135. Metric expansions close to an initial isotropic singularity in a Bianchi I space-time with kinetic matter

Ernesto Nungesser (Universidad Politécnica de Madrid)

Poster

Isotropic singularities are singularities which can be removed via a conformal rescaling which makes them attractive for physical and mathematical reasons to model the early universe. Ho Lee (Kyung Hee University), John Stalker (Trinity College Dublin) and Paul Tod (Oxford University) and myself have obtained metric expansions close to the initial singularity for Bianchi I solutions to the...

19. Micro Black Hole Dark Matter

Manuel Ettengruber (Institut de Physique Théorique)

Dark Matter

Talk

The influence of a possible low gravity scale, concretely through the presence of extra dimensions or additional species, on radiation properties of micro black holes is investigated. In particular, the suppression of evaporation through the so-called memory-burden effect is shown to be stronger, occurs earlier and with sharper transition compared to the canonical Planck-scale regime. It is...

52. Modelling correlated Si III absorption for precision measurements of the matter power spectrum from the Lyα forest

Ke Ma (University of Nottingham)

Methods / Statistical Inference / Machine Learning

Talk

The one-dimensional Lyα forest power spectrum is a powerful cosmological probe of matter density fluctuations in the weakly non-linear regime, providing leading constraints on the matter power spectrum and the nature of dark matter at small scales. A key astrophysical systematic, however, is contamination from correlated metal absorption, especially Si III. Standard treatments usually model...

321. Modified gravity & friends vs current CMB data.

Enrico Specogna (University of Sheffield)

Cosmic Microwave Background

Talk

In this talk we will look for evidence of the effects induced by seemingly different extensions to the standard cosmological model in the cosmic microwave background (CMB) primary and secondary anisotropies measured by the latest ACT, SPT and Planck releases: modified gravity (through the growth index - '$\gamma$', a modification of the growth of linear perturbations in the standard model, and...

288. Multi-messenger Cosmology with gravitational waves and NewAthena

Niccolò Passaleva (Sapienza University of Rome)

Gravitational Waves

Talk

The connection between gravitational wave (GW) sources, short gamma-ray bursts and their X-ray afterglows in GW170817 is a cornerstone for multi-messenger cosmology, allowing for an independent measurement of the cosmic expansion.

Gravitational wave signals alone cannot constrain the Hubble constant, H0, due to intrinsic degeneracies between redshift and the masses of the merging objects,...

24. Multi-soft theorems for cosmological correlators: Background wave method for scalars & gravitons

Dr Farman Ullah (International Centre for Theoretical Sciences (ICTS – TIFR), Bengaluru, India)

Inflation / Primordial Perturbations

Talk

Cosmological soft theorems (or consistency relations) provide a powerful probe
for the physics of inflation. These relations rely on minimal assumptions and hold very
generally. Consequently, any violation of these relations would rule out a large class of
inflationary models. For instance, a violation of the scalar soft theorem (or consistency
relation) would rule out all attractor...

76. Multi-Tracer Cross-Correlations of the Unresolved $\gamma-$ Ray Sky

Bhashin Thakore (University of Turin and the University of Amsterdam)

Large-Scale Structure

Talk

We present a study of the unresolved $\gamma$-ray background (UGRB) aimed at probing the nature of the faintest $\gamma$-ray source populations in the Universe. By leveraging statistical cross-correlations between the UGRB and tracers of large-scale structure, we assess the contributions of different source classes to this diffuse emission. Our analysis combines twelve years of Fermi Large...

337. Multifield Cosmological Collider Signal with a Twist and a Turn

Anmol Raina (Dept. of Physics Harvard University)

Poster

The presence of multiple massive scalar fields during inflation is often a generic prediction of UV complete theories of gravity. In addition to the top down motivation, multifield models of inflation also solve the “$\eta$-problem” by incorporating non-geodesic trajectories in the field space. Deviations of the inflaton’s trajectory from the geodesic, quantified by bending parameters,...

88. N-body Simulations of the EFT of Dark Energy with PySCo-EFT and ECOSMOG-EFT

Himanish Ganjoo (LUX, Observatoire de Paris)

Dark Energy / Modified Gravity

Talk

Modified gravity theories constitute viable alternatives to the standard cosmological model for explaining the observed late-time accelerated expansion of the Universe. The Effective Field Theory of Dark Energy (EFTofDE) is an efficient framework to describe a wide range of such theories with a limited number of parameters. To robustly constrain them by comparison with clustering and weak...

64. Nanohertz Gravitational Waves from the Baryon-Dark Matter coincidence

Jacopo Nava (Vrije Universiteit Brussels)

Gravitational Waves

Talk

The nanohertz gravitational-wave (GW) signal observed by pulsar timing arrays may originate from a cosmological first-order phase transition (FOPT) at temperatures of order 100 MeV. This coincidence raises a fundamental question: why this scale? We show that such a PT naturally arises in scenarios where the baryon asymmetry is generated from a dark asymmetry via resonant neutron-dark matter...

340. Negentropy contraints on primordial nongaussianity

Spyros Sypsas (Centro de Ciencias Exactas, Universidad del Biobio)

Cosmic Microwave Background

Talk

The CMB is gaussian, at least according to the estimators that have been used in surveys like Planck, which is the bispectrum and trispectrum. In recent years there have been various proposals of nongaussian signatures that spread through out the whole PDF of fluctuations, and in some cases cannot be captured by looking at lower n-point functions. We propose the negentropy as a single-point...

325. Neutralino Dark Matter Relic Density in Finite SU(5) with Starobinsky Cosmology

José Antonio Morales Álvarez (Instituto de Física, UNAM)

Dark Energy / Modified Gravity

Talk

We study the relic abundance of the lightest neutralino in Finite Unified Theory FUTB, a fully finite N=1 supersymmetric SU(5) model whose all-orders vanishing beta functions uniquely fix the soft SUSY-breaking spectrum in terms of a single gaugino mass parameter M. We couple this theory to Starobinsky R²-inflationary cosmology and systematically examine whether the observed dark matter...

239. Neutrino cross sections and non-standard interaction Implications

Anjan Giri (IIT Hyderabad)

Neutrinos

Talk

The question of whether neutrinos follow inverted or normal mass hierarchy and the CP violation parameter $\delta_{CP}$ in the neutrino sector (which may help understand the matter antimatter asymmetry etc.), are some of the important goals of current and future neutrino experiments. Cosmology provides constraints on total neutrino mass, $N_{eff}$ (and implications for mass hierarchy). ...

367. New constraints on sterile neutrino thermalisation

Nicola Barbieri (IFIC (CSIC-UV))

Neutrinos

Talk

In this work, we revisit the problem of sterile neutrino thermalisation for MeV reheating temperatures with the full oscillation paradigm of the 3+1 scheme, extending the analysis that we recently carried out in the absence of sterile neutrinos. For the first time, we consider the effect of all mixing angles, fixing those exclusive of active neutrinos to the values obtained in global-fit...

44. New tools for cosmology by Extended Theories of Electro-Magnetism (ETEM)

Alessandro Spallicci (Université d'Orléans - CNRS)

Dark Energy / Modified Gravity

Talk

Compatible with General Relativity (GR), the dark Universe lacks experimental confirmation and support by the Standard Model (SM). Opposing darkness, extensions of GR face the successes of GR. But photons, main messengers, are still read with the XIX Maxwell theory, although Quantum Electro-Dynamics (QED) requires non-linear corrections, e.g., photon-photon. Extended Theories of...

36. Non-Abelian Domain walls: oreo and CP violation

Bowen Fu (Northeastern University, China)

Early Universe

Talk

One of the most popular candidates for fermion flavour unification is the discrete flavour symmetry, including $A_4$, $S_4$, $A_5$, etc. The spontaneous breaking of discrete flavour symmetries can lead to the formation of domain walls, a kind of topological defect that can form during the phase transition in the early universe. We study this phenomenon in the scenarios of real and complex...

158. Non-Linear Dynamics and Primordial Black Hole Formation during Kination

Cheng Cheng (Center for Physical Sciences and Technology (FTMC))

Early Universe

Talk

The early universe may have experienced a kination epoch - a phase where a scalar field's kinetic energy dominates the expansion. In this talk, I will outline how scalar-field inhomogeneities during this era can trigger strong non-linear dynamics, and how these can collapse to form primordial black holes (PBHs). Based on numerical relativity simulations, I will show the conditions under which...

353. Non-Linear Effects of the Interacting Dark Energy Model

Yuejia Zhai (University of Sheffield)

Poster

We focused on a phenomenological interacting dark energy model (IDE) with energy-momentum transfer from dark matter to dark energy through a coupling $Q=\xi\mathcal{H}\rho_{DE}$. Following our previous work on constraining the parameters of the same IDE model using CMB and DESI data, we now present the N-body simulation results based on a modified version of RAMSES code. Compared with the...

265. Non-linear Relativistic Cosmology on the Observer’s Past Light-Cone

Pierre Béchaz (University of Pisa & INFN, Pisa)

Poster

With high-precision data about to be delivered by large-scale surveys, the development of higher-order perturbative descriptions of cosmological observables is becoming increasingly important. The Geodesic Light-Cone coordinates provide a natural framework for this purpose, as they are specifically adapted to the observer’s past light-cone and allow for a non-perturbative description of light...

304. Non-local inverse energy transfer in primordial magnetic field evolution

Lenard Kasselmann (Hamburg Observatory, University of Hamburg)

Primordial Magnetic Fields

Talk

Magnetic fields in cosmic voids could be of primordial origin, generated by early universe phase-transitions. During their turbulent decay, primordial magnetic fields (PMFs) might undergo inverse energy transfer, increasing their correlation length over time. Understanding this process is crucial for constraining PMFs, yet its physical mechanism is still debated, particularly in systems where...

41. Non-perturbative aspects of fermion reheating

Marcos Alejandro García García (Instituto de Física, UNAM)

Inflation / Primordial Perturbations

Talk

The transition from the inflationary phase to a radiation-dominated universe is typically a complex problem. The post-inflationary coherent oscillations of the inflaton field can drive the resonant growth of bosonic field fluctuations, including those of the inflaton itself, leading to backreaction and non-linear effects, and the eventual fragmentation of the homogeneous inflaton. These...

241. Nonlinear Evolution of Primordial Parity Violation

Sha Azyzy (Max Planck Institute for Astrophysics)

Poster

Parity violation is a new probe of the primordial universe. However, we need to connect the primordial universe to the observables. Recent hints of parity violation in the large scale structure of the universe motivate us to investigate how the observables are affected by late-time physical processes. In this work, we present an analytical expression for the parity violating 4-point...

251. Not so Minimal Warm Inflation

Mar Bastero Gil (University of Granada)

Inflation / Primordial Perturbations

Talk

An axion-like inflaton coupled to non-Abelian gauge bosons provides a compelling microphysical framework for warm inflation. Starting even from cold initial conditions, in these systems, sphaleron heating may generate thermal friction sufficient to sustain finite temperatures throughout the inflationary epoch. Insisting on shift-symmetric potentials, in this work we revisit the viability of...

254. Novel cosmological signatures of gravitons to photons and axions to photons conversion in the early universe

Rajeev Kumar Jain

Gravitational Waves

Talk

Circular polarization in the cosmic microwave background (CMB) offers a promising probe of the parity-violating physics of the early Universe. In this paper, we propose a novel method to constrain the primordial circular polarization of high-frequency gravitational waves (GW) in the GHz range. An efficient conversion of gravitons to photons in a transverse cosmological magnetic field at the...

351. Nucleation Rates for First-Order Phase Transitions in a Strict EFT Expansion

Nicholas Leister (Mainz University)

Poster

We present a systematic computation of bubble nucleation rates for cosmological first-order phase transitions within a strict EFT expansion obtained through dimensional reduction and the integration of fields heavier than the nucleation scale. The calculation consistently separates contributions from the leading EFT potential, higher-order operators generated by consecutive matching steps, and...

63. Numerical simulations of the stochastic formalism

Tomotaka Kuroda (IBS-CTPU-CGA/Institute of Science Tokyo)

Inflation / Primordial Perturbations

Talk

The stochastic formalism can be understood as an effective field theory for IR modes, which incorporates quantum corrections from UV modes at the coarse-graining scale. As the name suggests, the dynamics are described by Langevin equations. In general, the system is non-Markovian, meaning it depends on past history by construction in stochastic inflation.

In this talk, I will present and...

192. Observable Gravitational Waves and reheating in Quintessential Inflation with a self-resonant SU(2) Gauge Field

Hao-Yang Jin (Lancaster University)

Dark Energy / Modified Gravity

Talk

We investigate a model of quintessential inflation with a non-Abelian SU(2) gauge field, where the gauge kinetic function is modulated by the inflaton field. The backreaction onto the inflaton due to the gauge field yields a soft stiff period from the end of inflation to kination. This results in a characteristic gravitational wave spectrum that will be observable in the upcoming observations....

106. Observing gravitational waves without observing them

Jinn-Ouk Gong

Gravitational Waves

Talk

We argue that the coordinate redefinition necessarily introduces inevitable couplings between long- and short-wavelength modes. This leads to a unique footprint of the long-mode gravitational waves in the local scalar power spectrum. We discuss the observational prospects via the quadrupole moment of the local scalar power spectrum. Future Lyman-alpha and 21cm surveys are capable of detecting...

329. On EFT constraints from quasi-normal modes

Leonardo Juliano (Scuola Normale Superiore, INFN)

Dark Energy / Modified Gravity

Talk

Recently, a new bound on Effective Field Theories of gravity has been proposed, based on the stability of Black holes. The conjecture states that Black holes in modified gravity should always be more stable than their counterpart in General Relativity. I will show, using a simple power counting argument, that this condition does not provide any useful bound on EFT coefficients.

145. On the road for cosmology with Type I Supernovae from the Zwicky Transient Facility

Philippe ROSNET (LPCA, Université Clermont Auvergne & CNRS/IN2P3)

Dark Energy / Modified Gravity

Talk

The Zwicky Transient Facility (ZTF) is scanning the Northern sky since 2018 with a 1.2 m class telescope installed at the Mont Palomar Observatory. This survey detects any transient in the nearby Universe within its magnitude limit, typically up to a redshift of 0.15. In February 2025, the Cosmology working group has released a set of more than 3600 Type Ia supernovae (SN Ia) corresponding to...

289. One-point matter PDFs beyond TopHat filters

Alexander Kayssi (McMaster Universitry)

Poster

We study one-point probability distribution function (PDF) for averaged matter densities over spherical cells as a non-perturbative probe of the large-scale structure.  The PDF is analytically modelled using a path integral framework. It contains a leading order contribution controlled by the spherically symmetric gravitational collapse dynamics, as well as higher order contributions coming...

129. Open EFT for thermal inflation

Wenqi YU (IAS, HKUST)

Poster

We introduce thermal equilibrium condition in open EFT of inflation, and use this framework to explore the phenomenological aspects of thermal inflation. This talk includes three parts:
1. the dynamical KMS condition for open EFT of inflation and non-perturbative Green functions, including comparison with thermal field theory in de Sitter spacetime
2. The equilibrium constraints on EFT...

26. Open EFTs for Gauge Theories and Gravity

Prof. Andrew Tolley (Imperial College London)

Inflation / Primordial Perturbations

Talk

TBD

240. Optimal methods for cross-correlating projected and filtered tracers of large scale structure

Nathan Burwig (Arizona State University)

Poster

Cross-correlations between surveys which retain line-of-sight (LOS) structure - such as line-intensity-mapping (LIM) or spectroscopic surveys - and projected fields - such as CMB lensing - represent a powerful avenue for extracting cosmological information from next-generation experiments. Common approaches include tomographic binning of the radially-resolved field into 2D slices, projecting...

267. Oscillatory Signatures in Primordial Gravitational Waves from Double Sine-Gordon Inflation

Ms Behnoush Afshar (Research Institute for Astronomy and Astrophysics of Maragha)

Gravitational Waves

Talk

The imprint of inflation on primordial gravitational waves remains one of the most promising probes of the early Universe, offering a potential observational window into physics at otherwise inaccessible energy scales. In this study, the impact of non-trivial inflationary potentials on the primordial tensor power spectrum is investigated within the framework of standard single-field inflation...

328. Oscillon Stability in the Presence of Kinetic Coupling after E-model $\alpha$-attractor Inflation

Islam Khan (The University of Virginia's College at Wise)

Poster

We study post-inflationary oscillon dynamics in an E-model $\alpha$-attractor scenario in which the inflaton is kinetically coupled to an ultralight axion. We perform nonlinear three-dimensional lattice simulations using GABE to investigate how this interaction affects both the formation of oscillons and their subsequent evolution. We find that oscillons can still form in the presence of...

330. PANDA: A TreePM N-body code to simulate Horndeski models with a phenomenological screening.

Edoardo Martinelli (University of Bologna)

Dark Energy / Modified Gravity

Talk

In this talk, I will present the current status and first results of PANDA. PANDA is a modified version of the TreePM N-body solver Gadget-4, extended to include Modified Gravity within the Effective Field Theory framework, enabling simulations across the broad class of Horndeski theories. In particular, PANDA implements a mapping of general Horndeski models through a set of parameters...

27. Parameterizing Dark Energy at the density level: A two-parameter alternative to CPL

Gabriele Montefalcone (University of Texas at Austin)

Large-Scale Structure

Talk

Recent BAO observations from the DESI collaboration, combined with CMB and supernovae data, suggest a preference for evolving dark energy (DE) in place of a cosmological constant, particularly within the widely used CPL parameterization of the DE equation of state. In this talk, I present an alternative and complementary approach that instead describes the evolution of the DE density directly,...

273. Perturbative Modeling of Mixed Dark Matter Cosmologies

Safak Celik (Max Planck Institute for Astrophysics)

Large-Scale Structure

Talk

Large-scale structure is a powerful probe of dark matter beyond the standard cold paradigm, since even a subdominant warm component can leave observable signatures through its free-streaming effects. In mixed dark matter cosmologies, where cold and warm components evolve jointly, these effects generate not only total density fluctuations but also relative density and velocity perturbations...

141. Phantom-Crossing Dark Energy and the Ωm Tug-of-War

David Shlivko

Dark Energy / Modified Gravity

Talk

Recent analyses combining data from the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and Type Ia supernovae (SN) have revealed a tentative observational preference for phantom crossing in the dark energy equation of state $w$. We argue that this preference is a natural consequence of the $\Omega_m$ tensions that arise when these datasets are individually fit to...

161. Phase Transition Effects in Axion Abundance and Phenomenology

Galymzhan Baltabay (KBFI, Estonia)

Dark Matter

Talk

We study axion dynamics and relic abundance in first-order phase transitions, extending the bubble misalignment mechanism to a cosmological setting. In this setup, the axion mass turns on discontinuously inside expanding true vacuum bubbles. We perform lattice simulations of the axion field and identify two regimes. For fast transitions, the dynamics reduces to delayed misalignment, where the...

77. Physical properties and redshift distributions of KiDS-1000 galaxies using a generative galaxy population model

Anik Halder (University of Cambridge)

Methods / Statistical Inference / Machine Learning

Talk

Accurate redshift calibration and physically motivated source sample selection are central challenges for precision weak lensing cosmology. In this talk, I will present our recent work on forward modelling redshift distributions and inferring physical properties of weak lensing galaxies in the Kilo-Degree Survey (KiDS-1000) using a generative model for the galaxy population. The framework...

223. Positivity Constraints on the EFT of Inflation

Rafael Bravo Guerraty (Pontificia Universidad Católica de Chile)

Inflation / Primordial Perturbations

Talk

Positivity bounds derived from unitarity, locality, and causality constrain the Wilson coefficients of EFTs admitting a Lorentz-invariant UV completion. Extending these bounds to the EFT of inflation is nontrivial: cosmological observables are correlation functions rather than scattering amplitudes, the background is quasi–de Sitter rather than Minkowski, and Lorentz invariance is...

355. Precision tSZ Cluster Cosmology with the South Pole Telescope in the Era of Next-Generation Observations

Kayla Kornoelje

Poster

The unprecedented depth of current-generation CMB experiments enabled a window into studying the thermal Sunyaev-Zeldovich (tSZ) effect in a once inaccessible population of galaxy clusters. The newest instrument on the South Pole Telescope, SPT-3G, has produced CMB maps with noise levels of 3.2, 2.5, and 8.9 μK-arcmin at 95, 150, and 220 GHz, respectively. This has allowed for the detection of...

102. Preheating after a strongly supercooled phase transition in the early Universe

Mateusz Kulejewski (University of Warsaw)

Gravitational Waves

Talk

Preheating refers to a well-known set of phenomena, such as tachyonic instability and parametric resonance, associated with the dynamics of a scalar field, typically in the context of post-inflationary reheating. In this talk, I will explore the possibility of preheating-like amplification of fluctuations of a scalar field following a strongly supercooled electroweak first-order phase...

97. Primordial black hole evaporation in a thermal bath and gravitational waves

Dr Arnab Chaudhuri (Vellore Institute of Technology)

Poster

Primordial black holes (PBHs) formed in the early Universe evaporate via Hawking radiation and constitute a generic source of stochastic gravitational waves. Existing studies of gravitational wave production from evaporating PBHs typically assume vacuum evaporation, neglecting the fact that PBHs in the early Universe are embedded in a hot thermal plasma. In this work, we investigate...

103. Primordial black holes from inflation: on the decoupling between large and small scales

Dr Laura Iacconi (Queen Mary University of London)

Inflation / Primordial Perturbations

Talk

Primordial black holes can be produced from the collapse of large perturbations generated from inflation on scales much smaller than those seeding large-scale structure formation. It is possible that the large peak in scalar power at high wavenumbers might induce corrections to the scalar power spectrum on large scales, e.g. in the form of loop corrections, endangering the success of inflation...

215. Primordial Black Holes from Resonances in the Running-Mass-Inflation Model

Mindaugas Karciauskas (Center for Physical Sciences and Technology (FTMC))

Inflation / Primordial Perturbations

Talk

Resonant excitations during inflation can amplify the primordial curvature perturbation within a narrow range of k values. This suggest a novel mechanism to generate Primordial Black Holes (PBHs). We study such resonances within the context of the Running-Mass-Inflation model. Generated PBHs can explain the totality of Dark Matter. The mechanism also predicts the enhancement of induced...

336. Primordial Black Holes: Small Scales, Big Questions

Samuel Young (University of Sussex)

Early Universe

Talk

Primordial black holes (PBHs) may have formed from the collapse of large density fluctuations in the early Universe and provide a powerful probe of the primordial power spectrum on otherwise inaccessible scales. However, translating PBH abundances into constraints on primordial physics remains limited by theoretical uncertainties. A key source of this uncertainty is the choice of window...

7. Primordial Gravitational Waves from Scalar Backreaction in Axion-SU(2) Inflation

Dr Mattia Cielo (NORDITA)

Early Universe

Talk

In this work, we perform the first numerical study of strong scalar backreaction in spectator chromo-natural inflation (SCNI) in the case where the spectator sector decays during inflation. The tachyonic instability in scalar fluctuations, activated as the system crosses the $m_Q = \sqrt{2}$ threshold, amplifies perturbations and may significantly alter the background dynamics. The strong...

13. Primordial gravitational waves: A unique probe of dark matter

Debarun Paul (Indian Statistical Institute, Kolkata)

Dark Matter

Talk

Primordial gravitational waves (PGWs) serve as a unique window into the early Universe, offering a rare opportunity to bridge the gap between inflationary reheating and the microphysics of dark matter (DM). This talk explores how distinct PGW signatures can test novel physics scenarios beyond the standard model (SM), providing critical insights into the fundamental nature of the dark sector....

195. Primordial non-Gaussianity constraints on dissipative inflation

Bowei Zhang (University of Cambridge)

Cosmic Microwave Background

Talk

Dissipative effects appear in many early-Universe scenarios, yet their universal observational signatures and systematic confrontation with data remain largely unexplored. We employ the Open Effective Field Theory of Inflation (Open EFToI) to consistently incorporate dissipative and stochastic effects while preserving scale invariance. Dissipation enhances specific interaction channels of the...

140. Probing Effects of Feedback using the Cross-correlation of tSZ and CMB lensing maps from the South Pole Telescope

Ana Carolina Silva Oliveira (California Institute of Technology)

Cosmic Microwave Background

Talk

The thermal Sunyaev-Zeldovich (tSZ) effect and gravitational lensing of the cosmic microwave background (CMB) are powerful and complementary probes of cosmic structure formation: the former traces baryonic gas in galaxy clusters via Compton scattering, while the latter captures gravitational deflection by large-scale structure. Their cross-correlation constrains the relationship between...

324. Probing high-redshift structure growth: forecasts and first insights from Euclid AGNs and CMB Lensing Cross-Correlations

Matteo Peronaci

Cosmic Microwave Background

Talk

Measuring the growth of cosmic structure is a powerful test of the standard cosmological model. The Euclid mission is delivering an unprecedentedly deep sample of Active Galactic Nuclei (AGN), providing a unique large-scale structure tracer reaching far into the high-redshift universe. Here, we explore the cosmological potential of cross-correlating Euclid AGNs with CMB lensing ($\kappa$) maps...

293. Probing Inflationary and Reheating Signatures of the Double-Sine-Gordon Potential in General Relativity and Rastall Gravity

Ms Behnoush Afshar (Research Institute for Astronomy and Astrophysics of Maragha)

Poster

Cosmic inflation is one of the most successful frameworks for addressing the fundamental problems of the standard Big Bang model, including the horizon, flatness, and magnetic monopole problems. Among various inflationary scenarios, solitonic potentials, due to their topological features and dynamical stability, have attracted considerable attention in cosmological studies. This study...

134. Probing Modified Gravity and Cosmological Models: Impact of Systematic Effects

Paweł Siegmund (National Centre for Nuclear Research)

Dark Energy / Modified Gravity

Talk

The combination of the data from upcoming large-scale structure surveys - such as Euclid and the Rubin Observatory Legacy Survey of Space and Time (LSST) - and CMB lensing experiments - like the Simons Observatory - offers a powerful tool to test deviations from $\Lambda CDM$. Yet, the robustness of these tests depends on our understanding of observational and astrophysical systematics. In...

228. Probing Modified Gravity with Velocileptors and Cocoa: A Joint Analysis Pipeline for HSC-Y3 and BOSS DR12

Kohki Tanida (Nagoya University)

Poster

The standard $\Lambda$CDM model describes the evolution of the universe with remarkable success but relies on the enigmatic components of dark matter and dark energy. Recent cosmological tensions, such as the $S_8$ discrepancy, have further motivated the scientific community to perform stringent tests of General Relativity (GR) on large scales. Phenomenological modified gravity (MG)...

250. Probing spatial curvature and cosmic distance ladders model-independently: current status and forecasts

Arianna Favale (University of Rome Tor Vergata)

Poster

Model-independent approaches have gained increasing attention as powerful tools to investigate persistent tensions between cosmological observations and $\Lambda$CDM predictions. Building on our previous work, MNRAS 523 (2023) 3, 3406-3422, we present a follow-up analysis of the model-independent calibration of both the local and inverse distance ladders using cosmic chronometers (CCH) data...

262. Probing the absolute neutrino mass with PTOLEMY

Nicolo De Groot (Radboud University and Nikhef National institute for subatomic physics (NL))

Neutrinos

Talk

Determining the absolute neutrino mass scale remains a central challenge in cosmology and particle physics. The PTOLEMY experiment is designed to address this through precision spectroscopy of tritium beta decay. We will outline the experimental concept, focusing on two key innovations: a high-purity tritium target bound to graphene, and a novel, compact electromagnetic filter that reduces the...

86. Probing the Cosmic Web: A Multi-Wavelength Approach for Investigating Galaxy Cluster Pair Bridges

Rebecca Dudley (PhD Student at the University of Toronto)

Cosmic Microwave Background

Talk

A significant fraction of baryons in the universe live in diffuse large-scale structure, particularly in filamentary and bridge environments outside galaxy clusters. Galaxy cluster pairs and their connecting bridges provide an important laboratory for studying how matter flows between clusters and how heating, shocks, and feedback shape the intercluster medium. However, since these systems are...

51. Probing the Epoch of Reionization by reconstructing the velocity contribution to the patchy kSZ signal from 21-cm maps

Jelte Bottema (Rijksuniversiteit Groningen & Stellenbosch University)

Cosmic Microwave Background

Talk

Distinguishing between different reionisation histories requires observables that are sensitive to the timing and morphology of the Epoch of Reionization (EoR). We present a method to reconstruct redshift-dependent line-of-sight velocity fields from the 21-cm signal and use them to construct patchy kinematic Sunyaev--Zel'dovich (kSZ) maps that can be cross-correlated with the observed kSZ...

334. Probing the large scale structures of the Universe with GW observations

Sumit Kumar (GRASP, Utrecht University, Netherlands)

Gravitational Waves

Talk

Galaxy surveys have traditionally served as the primary probe of the large-scale structure (LSS) of the Universe. The rapidly growing catalog of gravitational-wave (GW) merger events now offers an independent and complementary probe for cosmological studies. Third-generation (3G) GW observatories, including the Cosmic Explorer and Einstein Telescope, are expected to detect thousands of compact...

226. Probing WIMP-nucleon Effective Interactions with Paleo-Detectors

Dionysios Theodosopoulos (The University of Texas at Austin)

Poster

Paleo-detectors offer a promising approach to the direct detection of WIMP dark matter via the readout of nuclear recoil damage tracks in natural minerals with ages on geological timescales of O(1 Gyr). These tracks act as a proxy for the recoil energy induced by WIMP–nucleus scattering. We present projections of the sensitivity of paleo-detectors to the full set of elastic and inelastic...

21. QCD corrections to the electroweak sphaleron rate

Philipp Klose (Nikhef)

Early Universe

Talk

The weak-isospin conductivity determines the rate of baryon number violating sphaleron processes in the high temperature phase of the Standard Model and is thus an important input for predictions of the primordial Baryon asymmetry. So far, only electroweak interactions were included in the computation of the conductivity. Presenting work published in 2510.20594, we for the first time also...

155. Quantum Imprints on Confinement: SU(N) Yang Mills Confinement PT at finite theta

Nicklas Ramberg (SISSA)

Gravitational Waves

Talk

We analyze the impact of a finite theta angle on the first-order confinement PT in SU($N_{c}$) Yang-Mills theory, where CP violation arises at $\theta = \pi$
due to the multibranched structure of the Yang-Mills vacuum. Using holography and lattice QCD inputs, we show that at finite
$\theta\,, N_{c}$, the supercooling regime of the metastable deconfined phase is reduced. We also study the...

93. Quantum Signatures of Cosmic Topology

Dr Anna Negro (Case Western Reserve University)

Early Universe

Talk

There are eighteen distinct topologies compatible with manifolds that admit a spatially flat Friedmann-Lemaître-Robertson-Walker metric. Seventeen of them--called non-trivial topologies--can be realized by introducing non-trivial topological boundary conditions. These boundary conditions constrain the allowed wavelengths of quantum fields living in such universes; consequently, non-trivial...

101. Rayleigh Scattering of CMB to constrain Primordial Magnetic Fields

Kwanit Gangopadhyay (University of Groningen)

Primordial Magnetic Fields

Talk

The presence of magnetic fields has been inferred in extragalactic spaces like voids, and astrophysical mechanisms are unable to explain the magnitude of these fields. This hints towards cosmological magnetic fields of primordial origin, that are amplified by the astrophysical dynamo effect.

As future surveys and telescopes provide higher precision measurements of CMB, LSS and EoR; we are...

33. Redshift space galaxy bispectrum multipoles as probes of neutrino mass and modified gravity

Sourav Pal (Indian Statistical Institute, Kolkata)

Dark Energy / Modified Gravity

Talk

Beyond two-point statistics, the galaxy bispectrum provides a sensitive probe of non-linear gravitational dynamics, redshift-space anisotropies, and physics beyond ΛCDM. We study redshift-space galaxy bispectrum multipoles as a probe of massive neutrinos and modified gravity, focusing on the Hu–Sawicki f(R) model. Using a spherical-harmonic decomposition of the bispectrum, we capture the full...

92. Repeated Stimulated Emission of Gravitational Waves in Primordial Black Hole Binaries

Tristan Weaver

Poster

It has been recently shown that gravitational waves incident on a compact object binary can stimulate excess gravitational wave emission under resonant conditions. In this work, we calculate the waveform of this stimulated emission. We investigate whether repeated stimulated emission of gravitational waves could lead to an exponential growth in coherent gravitational wave strength in a...

181. Revisiting the Hubble Constant with FRBs: New Clues in the Hubble Tension Debate

Surajit Kalita (Astronomical Observatory, University of Warsaw, Poland)

Methods / Statistical Inference / Machine Learning

Talk

Fast Radio Bursts (FRBs) are millisecond radio transients with high dispersion measures, making them powerful tracers of ionized matter across cosmological distances. In this talk, I present two complementary approaches, Bayesian analysis and machine learning, applied to a set of localized FRBs to rigorously test the consistency of the $\Lambda$CDM model at late cosmic epoch. Our results...

189. Robust CMB B-mode analysis with Needlet-ILC and simulation-based inference

Adriaan Duivenvoorden (Max Planck Institute for Astrophysics)

Methods / Statistical Inference / Machine Learning

Talk

Polarized Galactic emission is the foremost challenge for searches for a background of primordial gravitational waves imprinted in the polarization of the CMB. We argue that current methods struggle to address this challenge, either by being overly susceptible to model misspecification, or by failing to properly propagate the uncertainty due to residual Galactic emission after foreground...

10. Scalar-Induced Gravitational Waves: Beyond the Lattice

Ángel García Vega (Instituto de Física, UNAM)

Early Universe

Talk

We study a model in which scalar fields generate gravitational waves through 4-point correlation functions, originating from the scalar power spectrum. The resulting gravitational wave spectrum depends on the couplings of the scalar fields and is predominantly blue-tilted, which automatically satisfies the constraints on CMB scales.

The novelty of our approach lies in computing the...

150. Schwinger effect in axion inflation

Oksana Iarygina (Nordita)

Inflation / Primordial Perturbations

Talk

Axions are well-motivated pseudoscalar fields that arise in many extensions of the Standard Model and can drive inflation. In scenarios where an axion couples to a gauge sector during inflation, the rolling field can lead to exponential amplification of gauge-field fluctuations, with important implications for particle production, reheating dynamics, primordial gravitational wave signatures,...

70. Screened Forces in a QCD-Like Dark Sector on Galactic Scales

Mathilda Denison (University of Pennsylvania)

Dark Matter

Talk

Persistent small-scale challenges to the ΛCDM cosmological model have motivated the consideration of dark matter models with richer phenomenology. We consider a dark QCD scenario in which dark axions mediate a screened force between dark baryons within dark matter halos. Finite-density corrections to the dark QCD quark condensate introduce a density-dependent interaction term between dark...

352. Searching for Cosmic Topology with Bayesian Methods using the Likelihood

Linn Htat Lu (Imperial College London)

Methods / Statistical Inference / Machine Learning

Talk

The universe has a non-trivial topology if there exist non-contractible closed loops through space. If the length scale of the topology is comparable to that of the last scattering surface, then this would influence the statistics of the cosmic microwave background (CMB). Here, we discuss one method of searching for this signal—the likelihood search.
The covariance matrix describing the CMB...

314. Searching for cosmic topology with large-scale structure data

Deyan Mihaylov (Case Western Reserve University)

Large-Scale Structure

Talk

Cosmic topology remains one of the last frontiers of modern Cosmology. Recent theoretical developments, together with the rapidly growing volume and precision of cosmological data, now make it possible to probe the global shape of the Universe with greater sensitivity. While current and future cosmic microwave background (CMB) observations continue to provide powerful tests of topology, I will...

62. Searching for ultralight dark matter from terrestrial magnetic fields

Kimihiro Nomura (Kyoto University)

Dark Matter

Talk

We present a novel search for ultralight dark matter using terrestrial magnetic field measurements at frequencies below 100 Hz, focusing on dark photon dark matter as a representative candidate. Coherently oscillating dark photon dark matter can induce a monochromatic magnetic field via kinetic mixing with ordinary photons. Notably, for dark photon masses around 3 \times 10^{-14} eV, the...

369. Semi-Analytical Evolution of Axion Inflation Through Weak to Strong Backreaction

Aditya Kulkarni (University of Massachusetts, Amherst)

Poster

Axion inflation with a Chern-Simons coupling to gauge fields provides a well-motivated and phenomenologically rich realization of the early universe. The rolling axion tachyonically amplifies one gauge helicity, and for sufficiently large coupling this production becomes strong enough to back react on the axion background resulting in a non-linear axion evolution. In this work, we develop a...

3. Set the Night on FIRE: Building an Empirical Local Dark Matter Velocity Distribution

Xiuyuan Zhang

Dark Matter

Talk

The majority of terrestrial direct detection experiments for Dark Matter (DM) rely on the Standard Halo Model (SHM), which assumes the local DM velocity distribution follows a Maxwell–Boltzmann distribution. However, galaxy mergers can deposit DM that remains kinematically clustered today, inducing deviations from the smooth SHM prediction. Previous studies have suggested that the local...

231. Shapes and orientations of massive halos in the statistically anisotropic universe

Yurino Mizuguchi (Nagoya University)

Large-Scale Structure

Talk

Statistical isotropy is a foundational conjecture in cosmology. However, its validation is a critical task, as theoretical models involving vector fields, such as those in the early universe, naturally lead to its violation. While previous studies using CMB and galaxy clustering have placed constraints on the quadrupolar type of statistical anisotropy (SA), recent N-body simulations have...

175. Sigma meson bound-state transition in the early universe and O(N) model double-branch vacuum instability

Yuan-Lin Lyu (Peking University)

Poster

The restoration of the $SU(2)$ chiral symmetry is believed to occur at high temperatures, i.e., in the early universe. We generalize the $N/D$ dispersive method to finite-temperature scenarios to study the properties of the $\sigma$ meson observed in pion-pion scattering. The thermal $\sigma$ pole trajectory is obtained with cross-channel effects incorporated. The results predict a transition...

112. Signs of Love

Alessandro Longo (APC)

Gravitational Waves

Talk

The tidal deformability of compact objects, parameterized by their Love numbers, provides a crucial window into their internal structure and fundamental physics. In this talk, I will demonstrate that foundational principles impose strict constraints on these observables. Specifically, by exploiting the analytic properties of the tidal response function via a Kramers-Kronig dispersion relation,...

12. SIMPonium Bound States in the Early Universe: Solving the Cosmological Tensions

Gokhula Prasad (National Institute of Technology-Trichy)

Poster

Dark matter remains one of the most compelling mysteries in modern physics. While WIMPs have long been leading candidates, the lack of experimental evidence has motivated alternatives such as SIMPs. We consider an MeV scale complex scalar SIMP dark matter candidate $\chi$, interacting via a massless dark photon $A^\mu$, which induces a Coulomb potential and forms bound states...

198. Simulating magnetic fields inside and around galaxies with SWIFT code

Nikyta Shchutskyi (Leiden University)

Poster

Magnetic fields permeate the Universe across a wide range of scales and strengths. On galactic scales, they are amplified by turbulent dynamo processes, eventually saturating at dynamically important levels, and are subsequently transported into the circumgalactic medium by galactic winds. In realistic environments, this evolution involves both direct and inverse turbulent cascades, driven by...

32. Simulation-based Inference for cluster cosmology

Sut Ieng Tam (Institute of Physics, National Yang Ming Chiao Tung University)

Poster

Galaxy clusters provide a powerful probe of the growth of cosmic structure and the amplitude of matter fluctuations. We present a cosmological analysis of XMM-XXL galaxy clusters using Hyper Suprime-Cam (HSC) weak-lensing data within a simulation-based inference (SBI) framework. We jointly model the cluster redshift distribution, stacked weak-lensing profiles, and X-ray temperature and...

214. Simulation-Based Inference for Cosmological Field Reconstruction and Parameter Estimation

Oleg Savchenko (GRAPPA Institute, University of Amsterdam)

Methods / Statistical Inference / Machine Learning

Talk

Simulation-based inference (SBI) enables Bayesian analysis of complex cosmological data when only a forward model is available, while field-level inference (FLI) aims to perform inference in a maximally efficient way and retain more information than summary-statistic pipelines. In this talk, I will highlight recent advances and applications of SBI and FLI in cosmology. First, I will show how...

233. Simulations of the axion field in the kinetic misalignment scenario

Kenichi Saikawa (Kanazawa University)

Dark Matter

Talk

In the kinetic misalignment scenario for QCD axion dark matter, the axion carries significant kinetic energy in the early universe, which affects its dynamics at the epoch of the QCD phase transition and can lead to a significant amplification of primordial fluctuations due to the nonlinearities of the QCD potential. In this work, we present novel lattice simulations of the axion field to...

212. Skew-normal likelihood for non-Gaussian astronomical data

Zeynab Ashurikisomi (Leiden Observatory)

Methods / Statistical Inference / Machine Learning

Talk

Cosmological observables often exhibit mild but significant deviations from Gaussianity, typically in the form of asymmetric tails. Using Gaussian likelihoods in such cases can therefore introduce systematic biases in parameter inference. We investigate the use of a skew-normal likelihood as a flexible alternative that captures these non-Gaussian features.
We focus on cosmic shear 2 point...

333. SkyExplain: a framework for machine learning interpretability in cosmology

Guadalupe Cañas-Herrera (Leiden Observatory)

Methods / Statistical Inference / Machine Learning

Talk

We present a novel framework for cosmological model selection based on Neural Networks trained directly on simulated Cosmic Microwave Background (CMB) temperature and polarisation maps, as well as summary statistics.

A central component of this work is SkyExplain, an open-source framework designed to bring interpretability to machine learning applications on cosmological data. SkyExplain...

18. Slow force carriers in particle physics and cosmology

Francesco Serra (Johns Hopkins University)

Dark Energy / Modified Gravity

Talk

I show that gauge theory and gravity admit modifications in which all local symmetries are broken without introducing new scales, leading to new gapless modes universally coupled to matter. The new modes have small speed, which suppresses all their interactions with matter, making them compatible with current observations. The new slow forces provide a conservative channel of new physics...

182. Some Aspects of Cosmic Inflation and Gravitational Waves

Anjan Giri

Early Universe

Talk

Recent observations from ACT along with Planck and DESI give us better understanding of the early universe with cosmic inflation. The spectral index $n_s$, tensor-to-scalar ratio (r), $\omega$ and number of e-folds are inferred. In addition, we also have the late time acceleration expansion possibly attributing to the dark energy. We will consider the Starobinsky model to discuss as a modified...

199. Spatially covariant gravity theories with two degrees of freedom

Xian Gao

Dark Energy / Modified Gravity

Talk

General relativity propagates only two degrees of freedom (DOFs), and Lovelock's theorem strongly constrains possible alternatives. A natural way to explore modified gravity is to relax temporal diffeomorphism invariance while preserving spatial covariance. Such spatially covariant gravity theories, however, generically propagate an additional scalar mode. We will discuss three complementary...

30. Spectral decomposition in stochastic inflation

Eemeli Tomberg (UCLouvain)

Inflation / Primordial Perturbations

Talk

Stochastic inflation allows the study of large inflationary fluctuations, casting their evolution into the form of a Fokker-Planck equation. I discuss solving this equation using the spectral decomposition method, a technique underutilized in modern stochastic inflation studies. The method gives easy access to the late-time distributions of the inflaton field and its first-passage times...

45. Spectral Signatures of Multi-Mediator Astrophysical Neutrino Self-Interactions at Ultra-High Energies

Ayushi Kaushik (SHIV NADAR UNIVERSITY, GREATER NOIDA)

Neutrinos

Talk

We discuss the effect of multiple mediators influencing the scattering of astrophysical neutrinos at the ultra-high energies — 100 TeV and beyond — against relic neutrinos from the Cosmic neutrino background, demonstrating unique features in the resulting spectral shape as detected at neutrino telescopes like IceCube. We specifically discuss the effect of superposition of scattering amplitudes...

184. Spherically Symmetric Fluid Simulations of Black Hole Accretion in Self-Interacting Dark Matter Halos

Tan Chen (Beijing Normal University)

Dark Matter

Talk

We investigate black hole accretion in self-interacting dark matter (SIDM) halos using a self-gravitating fluid model with thermal conduction. We develop a robust one-dimensional spherically symmetric hydrodynamic code based on an operator-splitting finite-volume method. Simulating both Singular Isothermal Sphere (SIS) and Navarro-Frenk-White (NFW) profiles, we find that black hole growth is...

296. Staying focused: In-flight monitoring of the Euclid space telescope

Dennis Neumann (Leiden Observatory)

Poster

One of the Euclid survey’s primary cosmological probes is weak gravitational lensing: the apparent coherent distortion of galaxies caused by their light passing through gravitational potentials along the line of sight. Obtaining precise and accurate galaxy shapes is therefore crucial for unbiased cosmological inference. The leading source of systematic error in these measurements is the...

71. Stellar models in third order Lovelock gravity

Shavani Naicker (University of KwaZulu-Natal)

Poster

We present a spherically symmetric stellar model within the framework of seven dimensional third order Lovelock gravity for a neutral perfect fluid distribution. The third order Lovelock field equations are generated for such a fluid configuration by imposing pressure isotropy. This condition yields a first order nonlinear differential equation which is an extension of the Abel differential...

206. Stellar streams in the diffusion regime: a fast differentiable forward model for dark matter substructure inference

Noemi Anau Montel (Max Planck Institute for Astrophysics)

Dark Matter

Talk

Stellar streams are among the most sensitive probes of dark matter substructure on small scales, where the microphysical nature of dark matter could leave distinct signatures. When a stream is subjected to many encounters with low-mass substructure over its lifetime, the cumulative effect is well described by a diffusion regime in which velocity kicks accumulate as a random walk. We present a...

130. Stochastic Effects Beyond Inflation

Tays MIRANDA (Ecole Normale Supérieure)

Poster

I explore the extension of the stochastic formalism to non-inflationary early-universe scenarios, focusing on bouncing cosmologies with exponential scalar-field potentials. The framework is formulated directly in phase space, enabling a unified description across classical contraction and the bounce. I outline the conceptual and technical challenges involved in applying stochastic methods...

153. Stochastic inflation: typical assumptions and their validity.

Diego Cruces Mateo (Institute of Theoretical Physics - Chinese Academy of Sciences (ITP,CAS))

Inflation / Primordial Perturbations

Talk

Stochastic inflation provides a powerful framework for studying inflaton fluctuations in a non-perturbative regime. However, to make the problem tractable, the formalism relies on a number of simplifying assumptions. In this talk, I will explore these assumptions, focusing in particular on the construction of the noise terms, which are typically taken to be white and Markovian. I will then...

230. Stochastic instantons and the tail of the inflationary density perturbation

Jaime Calderon Figueroa (University of Sussex)

Inflation / Primordial Perturbations

Talk

In the stochastic $\delta N$ formalism, the statistics of the primordial density perturbations can be mapped onto the first-passage distribution of the underlying stochastic process. In this talk, I will present a general framework to evaluate the rare-event tail of this distribution, based on a saddle-point approximation of the associated path integral.
I will show that, at leading order,...

172. STOchastic LAttice Simulation of hybrid inflation

Tomoaki Murata (Tokyo Metropolitan College of Industrial Technology)

Poster

We investigate the spatial profile of the curvature perturbation generated in multi-waterfall hybrid inflation models, which are known to produce various topological defects. Using the lattice simulation code STOchastic LAttice Simulation, based on the stochastic formalism of inflation, we analyse six cases by varying the number of waterfall fields n and the functional form of the inflaton...

68. Stochastic relativity of dark energy: lessons from inflation

Yoann Launay (DAMTP, University of Cambridge)

Inflation / Primordial Perturbations

Talk

Previous work on Stochastic Inflation in full General Relativity is reviewed and showcased with latest numerical findings. The recipe to obtain the dynamics of a any such nonlinear and nonperturbative theory, when dynamically sourced by classicalised fluctuations of the short modes, is explained and extended to any scalar-tensor action described by the Effective Field Theory of Dark Energy....

364. Superhorizon Isocurvature as a Window into Dark Matter Production

Pedro Schwaller

Early Universe

Talk

Searches for neutrino isocurvature usually constrain a specific linear combination of isocurvature perturbations. We will discuss realistic cosmological scenarios and argue that in general both, neutrino and matter isocurvature perturbations are generated, whose ratio we parameterize by a newly introduced mixing angle. We obtain the first limits on this new mixing angle from PLANCK data, and...

148. SWIM: A Complete Numerical Framework for Assessing Warm Inflation Models

Umang Kumar (Ashoka University)

Poster

Warm inflation (WI) modifies the generation of primordial perturbations through dissipative dynamics and thermal fluctuations, making their accurate computation inherently challenging. Existing approaches typically rely on semi-analytical approximations in which the scalar power spectrum is expressed through a correction factor $G(Q)$ that depends only on the dissipation ratio $Q$. We present ...

327. Symbolic Emulation for Fast Inference in Modern Cosmology

David Vokrouhlický (CEICO FZU)

Methods / Statistical Inference / Machine Learning

Talk

Modern cosmology often requires repeated evaluations of expensive theoretical predictions, from inference and model comparison to forecasts and exploratory studies beyond ΛCDM. Symbolic regression offers a fast and accurate alternative for building emulators, competitive with traditional neural-network approaches while retaining compact analytical expressions that are transparent,...

237. Symplectic Bogoliubov Maps for CGPP in Lorentz-Breaking Proca–Scalar Cosmology

Dr Simón Riquelme (Universidad San Sebastián)

Poster

Cosmological particle production is commonly described with intermediate-time quasiparticle labels that cease to align with asymptotic constructions once evolution carries mode frequencies far outside adiabaticity. We analyze a coupled Proca–scalar model on spatially flat FLRW, retaining the longitudinal sector of the massive vector and quadratic mixing of scalar perturbations through...

343. Systematic evaluation of ground-state Scalar Field Dark Matter at dwarf galaxy scales

Aditya Verma (Newcastle University)

Poster

Halo density profiles in CDM follow a fixed functional form (e.g., NFW) that predicts over-dense cuspy inner regions compared with observed cores. Alternative DM models like Scalar Field (Fuzzy) Dark Matter (SFDM) aim to tackle this by producing cores balanced by quantum pressure and gravity. However, strong structure formation constraints on SFDM have motivated the need for Self-Interactions...

344. Systematic evaluation of ground-state Scalar Field Dark Matter at dwarf galaxy scales

Aditya Verma (Newcastle University)

Poster

Halo density profiles in CDM follow a fixed functional form (e.g., NFW) that predicts over-dense cuspy inner regions compared with observed cores. Alternative DM models like Scalar Field (Fuzzy) Dark Matter (SFDM) aim to tackle this by producing cores balanced by quantum pressure and gravity. However, strong structure formation constraints on SFDM have motivated the need for Self-Interactions...

246. Systematic uncertainties in optimal de-lensing of CMB B modes with cross-corrlation of CMB and galaxy survey

Kishan Deka (National Center for Nuclear Research, Warsaw)

Cosmic Microwave Background

Talk

In the era of high-precision Cosmic Microwave Background (CMB) anisotropy measurements, detection of primordial gravitational waves (PGWs) will be one of the main goals of current CMB experiments. Detection of a divergence-free (B-mode) component in CMB polarisation will provide direct evidence of inflationary PGWs in the early universe. However, weak gravitational lensing of CMB photons due...

299. Tachyonic encore: A universal shift of inflationary observables

Diogo Severino Gorgulho (University of Groningen)

Early Universe

Talk

We propose a generic, largely inflaton‑potential–independent mechanism in which a light axion spectator, initialized near the hilltop of its potential, reshapes inflationary observables through purely gravitational multi‑field dynamics. During inflation the axion is frozen and the background follows an effectively single‑field trajectory. After inflation ends the axion rolls, inducing a turn...

301. Tachyonic encore: A universal shift of inflationary observables

Diogo Severino Gorgulho (University of Groningen)

Poster

We propose a generic, largely inflaton‑potential–independent mechanism in which a light axion spectator, initialized near the hilltop of its potential, reshapes inflationary observables through purely gravitational multi‑field dynamics. During inflation the axion is frozen and the background follows an effectively single‑field trajectory. After inflation ends the axion rolls, inducing a turn...

202. Tachyonic production of dark relics: quantum 2PI formalism with momentum exchanging collisions

Olli Väisänen

Dark Matter

Talk

Oscillating spacetime curvature can drive the production of dark matter during reheating, and accurately quantifying this requires the use of both non-perturbative and non-equilibrium methods. This tachyonic instability has previously been studied using 2-particle irreducible -formalism in the Hartree approximation. However, modelling the non-thermal dark matter distribution and its subsequent...

259. Target Selection of Subaru PFS Cosmology Survey

Jingjing Shi (Kavli IPMU)

Poster

The Subaru Strategic Program PFS Cosmology Survey started observation from 2025. I will introduce the science, target selection of this survey and the major progress we have.

43. Test

Matthieu Schaller (Lorentz Institute & Leiden Observatory)

Poster

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277. Test4

Matthieu Schaller (Lorentz Institute & Leiden Observatory)

Poster

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157. Testing FLRW Without a Ruler: A Calibration-Free Null Test from Anisotropic BAO

Domenico Sapone (Department of Physics, FCFM, University of Chile)

Poster

Baryon acoustic oscillation (BAO) measurements are a cornerstone of late-time cosmology, but their interpretation typically relies on assumptions about the sound horizon and a background model. We show that anisotropic BAO data alone already enable a direct, calibration-free test of the underlying geometry.

We derive an exact null relation for flat FLRW spacetime written entirely in terms...

312. Testing the equivalence principle in galaxy surveys: a matter of time and two fluids

Sveva Castello (Max Planck Institute for Astrophysics)

Dark Energy / Modified Gravity

Talk

Does dark matter experience gravity in the same way as ordinary matter? By throwing different objects from the Pisa tower, Galileo showed that they were all subject to the same acceleration, hence providing a demonstration of the so-called weak equivalence principle. However, the validity of this principle for dark matter remains a key open question, which is rarely addressed in cosmological...

81. The bearable inhomogeneity of the baryon asymmetry

Dr Majid Ekhterachian (Scuola Normale Superiore, Pisa)

Early Universe

Talk

I will discuss the implications of precision measurements of light element abundances in concordance with the Cosmic Microwave Background for scenarios of physics beyond the Standard Model that generate large inhomogeneities in the baryon-to-photon ratio. I will show that precision Big Bang Nucleosynthesis (BBN) can constrain mechanisms that produce large scale inhomogeneities at temperatures...

316. The Canadian Galactic Emission Mapper (CGEM): Overview and Early Observations

Joshua MacEachern (National Research Council of Canada)

Cosmic Microwave Background

Talk

Gravitational waves from inflation may have left a detectable signature in the parity-odd, “B-mode” component of the polarization of the Cosmic Microwave Background (CMB). Detecting B-modes in the CMB would be “smoking gun” evidence for inflation and would probe some of the highest-energy physics in the known universe. However, current experiments have placed stringent upper limits on B-modes....

200. The challenges of using Baryon Acoustic Oscillations distances for cosmology

Stefano Anselmi (INFN, Sezione di Padova)

Large-Scale Structure

Talk

One of the landmarks guiding our understanding of physical cosmology is the large-scale structure, defined as the large scale distributions of galaxies, as observed by galaxy surveys. In this context, the so-called Baryon Acoustic Oscillations, are considered one of the most powerful cosmological probes. They are generally deemed to provide distance measures independent of a specific...

25. The Diffuse Supernova Neutrino Background in the presence of Secret Neutrino Interactions

Praveen Bharadwaj (Indian Association for the Cultivation of Science)

Neutrinos

Talk

The Diffuse Supernova Neutrino Background (DSNB) constitutes a steady and isotropic flux of neutrinos originating from all past core-collapse supernovae across the observable universe. Despite decades of theoretical development and increasingly stringent limits from experiments such as Super-Kamiokande, the DSNB remains undetected. Its eventual observation would provide a unique probe of...

111. The Effect of Dark Energy on the Void-Galaxy Alignments

Jounghun Lee

Dark Energy / Modified Gravity

Talk

We numerically explore if and how the nature of dark energy affects the strength of the tendency that the shapes axes of galactic halos located on void surfaces have perpendicular alignments with the directions toward the void centers. The alignment tendency of void-surface halos is quantified by the correlation parameter, $d_{t}$, that enters the analytic formula derived by Lee (2018) for...

131. The Effect of QSOs on Cosmological Parameter Estimates Using the Lyman-$\alpha$ Forest

Prof. Avery Meiksin (IfA, Edinburgh)

Large-Scale Structure

Talk

The Lyman-$\alpha$ forest provides constraints on cosmological models on both small spatial scales and large. Because the Ly$\alpha$ forest traces ionized intergalactic hydrogen, its statistical signatures are sensitive to both the metagalactic photoionization rate and the intergalactic gas temperature. The large-scale influence of QSO sources effects both of these. We show that QSO heating...

173. The Entangled State from a cosmological Euclidean Wormhole

Wei-Chen Lin (Ewha Womans University)

Poster

We use the Euclidean path-integral method to approximate the wave function of the Universe and consider the particular scenario in which a Euclidean wormhole instanton dominates. This Euclidean wormhole solution connected to Lorentzian manifolds provides an approximation to the emergence of a classical spacetime in the quantum cosmological treatment. Beyond the background level, perturbations...

139. The Glow of Axion Quark Nugget Dark Matter: CMB Spectral and Anisotropy Signatures

Fereshteh Majidi (University of British Columbia)

Cosmic Microwave Background

Talk

I would like to present a talk on the impact of early Universe energy injection on the Cosmic Microwave Background (CMB), with a focus on spectral distortions and anisotropies, using Axion Quark Nuggets (AQNs) as a concrete dark matter scenario.

In this work, I investigate how interactions between dark matter and baryons can lead to energy injection before recombination, and how this...

218. The Impact of Photo-z Bias on Cosmology with Weak Lensing Peak Counts

Arthur Whyley

Poster

Measuring the peaks of weak lensing convergence maps provides information about structure formation and the distribution of matter, which can improve cosmological constraints when combined with 2-point statistics. In a photometric survey, such as LSST, calibration of galaxy redshifts is expected to contribute significantly to the uncertainty on cosmological parameter estimation. To assess the...

197. The Linear Point Standard Ruler and Its Application to the Euclid Survey

Francesca Passalacqua (INFN Padova)

Large-Scale Structure

Talk

The large-scale distribution of galaxies encodes information about acoustic waves that propagated in the primordial baryon–photon plasma, leaving a characteristic feature in the two-point correlation function at scales of order 150 Mpc. By exploiting this feature, a new observable, known as the Linear Point, has been identified and shown to be a powerful cosmological standard ruler.

In...

318. The lyman-alpha Forest constraints on primordial black holes as dark matter candidates

Patricio Colazo (IATE)

Dark Matter

Talk

Primordial black holes (PBHs) remain a viable candidate for Dark matter. The goal of this work is to constrain their parameter space with a new fundamental probe, the Lyman-alpha forest, which depends on two parameters, the reionization history and thermal history of the universe. We adopt extended mass functions for the PBH mass distribution. To implement the effect of PBHs in cosmological...

295. The path to realistic SIMP dark matter

Daniil Krichevskiy (University of Stavanger)

Dark Matter

Talk

Strongly interacting dark sectors with pseudo–Nambu–Goldstone bosons provide a compelling and versatile framework for sub-GeV dark matter. While the original SIMP paradigm emphasizes number-changing $3\to2$ processes as the primary mechanism for setting the relic abundance, the phenomenology of pionic dark matter is significantly richer. Depending on the mass spectrum and interaction...

154. The POLONAISE Dark Matter experiment in Leiden

Prof. Christopher Tunnell (Rice Universtity)

Dark Matter

Talk

Quantum sensing has matured rapidly into a competitive platform for fundamental physics, and arrays of mechanical sensors are now positioned to test well-motivated dark matter scenarios long considered out of experimental reach. I will discuss POLONAISE, a magnetic-levitation experiment at Leiden University that re-purposes cryogenic vibration-isolation hardware originally developed for the...

261. The post-inflationary axion mass in a minimal scaling model

Prof. Mark Hindmarsh (University of Helsinki, University of Sussex)

Early Universe

Talk

We calculate the dark matter axion mass in the post-inflationary scenario in a minimal model with a set of numerical simulations on $12288^3$ grids, the largest to date. The minimal model contains only one extra scalar field which breaks the Peccei-Quinn U(1) symmetry at a temperature $f_a \sim 10^{11}$ GeV, creating a string network, which is assumed not to have a Standard Model Higgs...

127. The role of mergers shaping Halo Morphology

Ayan Nanda (NISER, BHUBANESWAR, INDIA)

Poster

We investigate the role of mergers in shaping the structural evolution of dark matter halos. Focusing on well-resolved halos in the mass range $10^{11.0}$–$10^{12.5}M_\odot/h$, we track their main progenitor branches across cosmic time. We find a clear evolutionary trend in halo morphology: halos that are oblate or triaxial at present predominantly originate from a prolate phase, while halos...

20. The SABRE South Experiment at the Stawell Underground Physics Laboratory

Peter McNamara

Dark Matter

Talk

SABRE is an international collaboration that will operate similar particle detectors in the Northern (SABRE North) and Southern Hemispheres (SABRE South). This innovative approach aims to distinguish potential dark matter signals from seasonal backgrounds: a pioneering strategy only feasible with a Southern Hemisphere experiment. SABRE South is located at the Stawell Underground Physics...

245. The spectrum of axions in a scaling string network

ASIER LOPEZ EIGUREN (University of the Basque Country)

Dark Matter

Talk

Cosmic strings formed after Peccei–Quinn symmetry breaking are expected to radiate axions throughout their evolution, playing a central role in determining the axion relic abundance and guiding experimental searches. A precise understanding of the string network dynamics and the resulting axion spectrum is therefore essential.

In previous work, we established that axion string networks...

191. The status of QUIJOTE telescopes: scientific results from the MFI, commissioning and cosmological forecasts for the TFGI

Mateo Fernández Torreiro (Universidade da Coruña, CITIC)

Cosmic Microwave Background

Talk

Titulo: The status of QUIJOTE telescopes: scientific results from the MFI, commissioning and cosmological forecasts for the TFGI

One of the main goals of current Cosmic Microwave Background (CMB) experiments is the detection of primordial B-modes, generated by gravitational waves during inflation. Achieving such a detection requires observations with exquisite polarization sensitivity,...

354. The Universe is Not Statistically Isotropic

Glenn David Starkman (Case Western Reserve University (US))

Cosmic Microwave Background

Talk

We have long celebrated the great success of cosmology in predicting the observed properties of the cosmic microwave background. And yet, for over two decades there has been consistent and slowly mounting evidence that on large scales the CMB is anomalous. The evidence is consistent from experiment to experiment and it implies the violation of statistical isotropy. I will discuss this...

166. Thermodynamics and quantum effects of de Sitter black holes

Lars Aalsma (University of Minnesota Duluth)

Inflation / Primordial Perturbations

Talk

The thermodynamics of black holes in de Sitter space is complicated by the presence of multiple horizons and the absence of a globally defined timelike Killing vector. In this talk, I will revisit existing proposals for thermodynamic identities describing charged black holes in de Sitter space and discuss their shortcomings. In particular, the conventional choice of normalization of the...

222. Three-point intrinsic alignments of galaxies and haloes in the FLAMINGO simulations

Casper Vedder (Leiden University)

Large-Scale Structure

Talk

Cosmic shear is a central probe of the late-time Universe, but the interpretation of its measurements is limited by astrophysical systematics such as intrinsic alignments (IA) of galaxies. Upcoming lensing surveys will enable measurements of higher-order statistics with increased precision, providing non-Gaussian information beyond two-point correlations. Interpreting these measurements...

42. Time-reversed Stochastic Inflation

Baptiste Blachier (UCLouvain (CURL) and LPENS)

Poster

Cosmic inflation may exhibit stochastic periods during which quantum fluctuations dominate over the semi-classical evolution. Extracting observables in these regimes is a notoriously difficult program as quantum randomness makes them fully probabilistic.

We propose a new way of framing Stochastic Inflation by enforcing the point of view of a local observer for which inflation has ended i.e....

236. To log, or not to log: Scaling solutions for axion strings

Carlos Martins (CAUP)

Dark Matter

Talk

The axion was proposed as a solution to the strong CP problem and is currently one of the main candidates for cold dark matter. Superficially, recent field theory simulations disagree on whether the number of axion strings per Hubble patch is constant or log dependent, as well as what form that log dependence might take. This is of particular relevance since this parameter strongly impacts the...

193. Toward a consensus picture of baryon feedback: Joint X-ray, Sunyaev-Zeldovich, and weak lensing measurements

Jared Siegel Siegel (Princeton University)

Large-Scale Structure

Talk

There is no consensus on how baryon feedback shapes the underlying matter distribution from either simulations or observations. We confront the uncertain landscape by jointly analyzing the kinetic and thermal Sunyaev-Zel’dovich effects and X-ray gas mass fractions, each characterized with galaxy-galaxy lensing. Across group and clusters masses and between $0<z<1$, we find consistent evidence...

162. Toward Robust LSST Cosmology: Data-Augmented Redshift Calibration and Efficient Marginalisation

Yun-Hao Zhang (Leiden University)

Methods / Statistical Inference / Machine Learning

Talk

The unprecedented statistical power and imaging depth of the Vera C. Rubin Observatory's LSST will enable transformative tests of ΛCDM and the nature of dark matter and dark energy. Realising this potential hinges on accurately estimating ensemble redshift distributions and efficiently marginalising over their uncertainties.
I will present a new framework for photometric redshift calibration...

99. Towards a Detection of Post-Born Lensing

Ewan Chamberlain (University of Sussex)

Cosmic Microwave Background

Talk

Weak gravitational lensing is a well-studied and valuable cosmological probe. Due to the complex path taken by a multipally-lensed photon, weak lensing analysis generally integrates the gravitational potential along the line of sight. This is known as the Born approximation. Accurately accounting for the effects from multiple weak lensing events requires the use of post-Born corrections....

346. Triggered phase transitions and gravitational waves

Aleksandr Chatrchyan (Stockholm University)

Early Universe

Talk

Cosmic phase transitions are a key source of gravitational waves and are usually assumed to be controlled by temperature. We study scenarios in which the transition is instead triggered by the dynamics of an additional scalar field. This setup allows for qualitatively new possibilities, including delayed transitions and symmetry restoration at low temperatures. In particular, we focus on...

260. Ultra-High-Energy Neutrinos, Primordial Black Holes, and Implications for the 21-cm Signal

Mansi Dhuria (Pandit Deendayal Energy University Gandhinagar, Gujarat, India)

Neutrinos

Talk

In this talk, we will investigate the origin of the ultra-high-energy neutrino event KM3-230213A (∼220 PeV) and the high-energy flux observed by the IceCube Observatory within a unified framework in which superheavy dark matter (DM) is produced via primordial black hole (PBH) evaporation and subsequently decays into neutrinos. We will discuss constraints on the PBH initial abundance parameter...

303. Unbiased Bayesian Inference of Peculiar Motions of Galaxies from Type Ia Supernovae Observations

Ujjwal Upadhyay

Poster

The peculiar motions of galaxies are powerful cosmological probes that trace the growth of structures and the distribution of matter in the universe, providing a means to investigate the nature of dark energy and test gravity on cosmological scales. However, their direct observation is extremely challenging, as it requires independent and precise distance measurements to galaxies. We present a...

242. Understanding stochastic gravitational wave backgrounds by exploring the parameter space of first-order phase transitions with the Sound Shell Model

Mika Mäki (University of Helsinki)

Gravitational Waves

Talk

Cosmological first-order phase transitions can generate stochastic gravitational wave backgrounds that provide a window into the early universe at the electroweak scale. The upcoming Laser Interferometer Space Antenna (LISA) will be sensitive to the mHz frequency band of these gravitational waves, providing a probe of physics beyond the Standard Model (BSM). Extracting the phase transition...

358. Unifying the astrophysical gravitational-wave background and foreground for cosmological inference

Bryce C

Gravitational Waves

Talk

The Hubble tension is a major cosmological problem, wherein early- and late-universe measurements of the Hubble constant are significantly discrepant. This tension can be probed by developing new measures of the Universe's expansion. In recent work, we created the stochastic siren, a novel way to measure the Hubble constant using the gravitational-wave (GW) background (GWB) arising from binary...

204. Unitarity in the non-relativistic regime and implications for dark matter

Marcos Flores (University of Oslo)

Dark Matter

Talk

Unitarity imposes strict bounds on elastic and inelastic partial-wave cross sections. However, state-of-the-art calculations, motivated by dark-matter phenomenology, may exhibit substantial violations of partial-wave unitarity, with potentially significant consequences for phenomenological predictions.

In this talk, I present a new, model-independent formalism that restores unitarity...

66. Universality and Criticality in Massless Scalar Field Collapse

Koushiki Bhattacharyya (Ahmedabad University)

Poster

The presentation is based on [1], where we study the unhindered gravitational collapse of a massless scalar field—one of the fundamental matter fields determined by a Lagrangian formulation—in a spherically symmetric spacetime, working in a frame-independent and ansatz-independent formalism.

We identify a single dimensionless parameter that determines the end-state, which can be one of the...

183. Unlocking Non-Gaussian Information in Weak Lensing: Optimal Tomographic Statistics for Euclid”

Andreas Tersenov (ICS&IA-FORTH/CEA-Saclay)

Methods / Statistical Inference / Machine Learning

Talk

Weak gravitational lensing is a primary probe for Stage IV cosmology, but fully exploiting upcoming surveys such as Euclid requires going beyond the standard power spectrum. Higher-order statistics (HOS) can capture the non-Gaussian information in tomographic data, yet two major challenges remain: their sensitivity to complex astrophysical systematics, and their reliance on computationally...

28. Unlocking the small-scale Universe: a roadmap to next-generation baryonic feedback modeling

Leah Bigwood

Large-Scale Structure

Talk

Uncertain modeling of baryonic feedback, how energy from active galactic nuclei and supernovae redistributes gas within and beyond halos, poses a major obstacle to testing the cosmological model with large-scale structure (LSS) probes that extend into the non-linear regime. Indeed, it represents the dominant source of uncertainty limiting the cosmological precision of weak lensing (WL).
In...

17. Unstable Dark Matter and Halo Abundance: A Spherical Collapse Approach

Thomas Montandon (Laboratoire Univers et Particules de Montpellier)

Dark Matter

Talk

Decaying dark matter (DDM) provides a well-motivated extension of $\Lambda$CDM, in which two-body decays -- characterized by a decay rate $\Gamma$ and velocity kick $v_k$ -- naturally suppress structure growth and lead to lower clustering amplitudes consistent with weak lensing measurements of $S_8$. Previous analyses combining Planck, BAO, and weak lensing data identified viable parameter...

313. UV artefacts in ultra-slow-roll models of inflation

Gerald Barnert

Poster

Within single-field inflation, primordial black hole and scalar-induced gravitational wave production from enhanced primordial perturbations typically requires a transient non-attractor phase, such as ultra-slow roll. We investigate the physical consistency of modelling such scenarios through analytical Hubble-flow parametrisation. By reconstructing the underlying scalar field potential, we...

338. Vector induced Gravitational Waves sourced by Primordial Magnetic Fields

Anish Ghoshal (University of Warsaw, Poland)

Primordial Magnetic Fields

Talk

In this work, we develop a generic formalism for the study of tensor perturbations induced at second order by first-order vector metric perturbations, dubbing these induced tensor modes vector-induced gravitational waves (VIGWs). Notably, considering an inflation-inspired power-law type magnetic field power spectrum of the form PB(k)∝knB (where nB is the magnetic spectral index), we show that...

185. Weak-Lensing Shear-Selected Galaxy Clusters in the Hyper Suprime-Cam Subaru Strategic Program and their Cosmological Applications

I-Non Chiu (National Cheng Kung University)

Large-Scale Structure

Talk

I will present cosmological constraints using the abundance of weak-lensing shear-selected galaxy clusters identified in the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The clusters are selected on the mass maps constructed using the latest three-year (Y3) weak-lensing data covering an area of ≈ 500 deg2, yielding in a sample size of 129 clusters with a high signal-to-noise ratio 𝜈 of 𝜈...

94. What if quantum nature of primordial gravitational waves survives?

Jiro Soda (Kobe university)

Gravitational Waves

Talk

During inflation, quantum fluctuations of spacetime, so-called primordial gravitational waves, are generated. We study its impact on gravitational waves from binary black holes under the assumption that the squeezing of primordial gravitational waves survives until the present. We show the squeezing of the quantum state of gravitational waves tells us the information of inflation.

370. When Tiny Halos Stir Spacetime : Gravitational Waves from Fifth-Force Mergers

Xinpeng Wang (IPMU)

Gravitational Waves

Talk

Dark matter fermions interacting via attractive Yukawa forces mediated by a light mediator can form dark matter halos in the very early universe. We show that bound systems composed of these halos are capable of generating gravitational wave (GW) signals detectable today, even when the individual halos are significantly lighter than the solar mass. The Yukawa force dominates the dynamics of...

171. Where Galaxies Point: First Measurement of the Large-Scale Axial Intrinsic Alignment

Pedro da Silveira Ferreira (Zhejiang University)

Large-Scale Structure

Talk

We present evidence for a large-scale axial intrinsic alignment (LAIA), a coherent preferred orientation shared by galaxies and cosmic-web filaments. LAIA provides a new statistical-isotropy test based on the orientation field of galaxy-scale and filamentary structures, complementary to CMB- and large-scale-structure-based probes of the cosmological principle. Applying a new estimator to the...

235. WimPyDD and WimPyC: Phython codes exploiting the complementarity between WIMP direct detection and indirect detection

Sunghyun Kang (CQUeST, Sogang University)

Dark Matter

Talk

I introduce WimPyDD and WimPyC which are object-oriented and customizable Python codes that calculate accurate predictions for the expected rates in WIMP direct detection experiments and WIMP capture rate in celestial bodies as indirect detection within the framework of Galilean invariant non-relativistic effective theory. Due to the experimental threshold direct detection can not explore...