Conveners
Contributed talks
- Chair: Elisa Todarello
Contributed talks
- Chair: Swagat Mishra
Contributed talks
- Chair: Antonio Padilla
Contributed talks
- Chair: Oliver Gould
Contributed talks
- Chair: Sergio Sevillano Munoz
Contributed talks
- Stephen Green (University of Nottingham)
Contributed talks
- Chair: Miguel Bezares
Contributed talks
- Chair: Jorma Louko
Contributed talks
- There are no conveners in this block
Contributed talks
- There are no conveners in this block
-
Joaquim Gomes (University of Liverpool)07/04/2025, 10:50UK CosmoTalk
We analyze theories that do not have a de Sitter vacuum and cannot lead to slow-roll quintessence, but which nevertheless support a transient era of accelerated cosmological expansion due to interactions between a scalar ϕ and either a hidden sector thermal bath, which evolves as dark radiation, or an extremely light component of dark matter. We show that simple models can explain the...
Go to contribution page -
Neel Shah (University of Portsmouth)07/04/2025, 11:10UK CosmoTalk
Cosmological constraints on modified gravity typically need to assume parametrisations that heavily restrict the functional forms of the independent degrees of freedom. They are also subject to assumptions about the background expansion history, the speed of gravitational waves, and theoretical priors such as shift symmetry and stability in a gravitational wave background. I show the impact of...
Go to contribution page -
Adam Smith (University of Sheffield)07/04/2025, 11:30UK CosmoTalk
Axion-dilaton models provide a well-motivated, minimal class of models
Go to contribution page
for which kinetic interactions between multiple scalar fields and their
predictions can be explored, in particular in late time cosmology. I will present the cosmological implications of these interactions when prescribing an axion and a dilaton field to describe dark matter and dark energy, respectively, including the... -
Barry Ginat (University of Oxford)07/04/2025, 11:50UK CosmoTalk
The matter power spectrum, $P(k)$, is one of the fundamental quantities in the study of large-scale structure in cosmology. In this talk, I will study its small-scale asymptotic limit, and give a theoretical argument to the effect that, for cold dark matter in $d$ spatial dimensions, $P(k)$ has a universal $k^{-d}$ asymptotic scaling with the wave-number $k$, for $k \gg k_{\rm nl}$, where...
Go to contribution page -
Irene Abril-Cabezas (University of Cambridge)07/04/2025, 15:50UK CosmoTalk
A major challenge in the analysis of Cosmic Microwave Background (CMB) data is posed by the presence of Galactic foregrounds, especially thermal dust emission. Both the search for primordial B-modes and measurements of structure growth rely on foreground modelling, for which most works implicitly assume that all sky components follow Gaussian statistics. However, we know that this is a poor...
Go to contribution page -
Raphael Kou (University of Sussex)07/04/2025, 16:10UK CosmoTalk
The discrepancy between local measurements of the Hubble constant and inferences from CMB and galaxy clustering data, known as the 'Hubble tension', has motivated numerous models introducing additional components active before recombination. While many such models have been proposed, none are currently strongly favoured by data. This highlights the critical role of upcoming CMB experiments,...
Go to contribution page -
Jade Piat (University of Edinburgh)07/04/2025, 16:30UK CosmoTalk
Understanding the accelerated expansion of the Universe remains as one of the key challenges in cosmology. The main candidates to explain this observation, which do not rely on a cosmological constant, are dark energy and modifications of General Relativity, but they require robust tests on cosmological scales. The Dark Energy Spectroscopic Instrument offers unprecedented precision in...
Go to contribution page -
Sophie Hoyland (Institute of Cosmology and Gravitation, University of Portsmouth)07/04/2025, 16:50UK CosmoTalk
Accurate predictions of weak lensing observables are essential for understanding the large-scale structure of the Universe and probing the nature of gravity. In this talk, I will present a lightcone implementation to generate maps of the weak lensing convergence field using the COmoving Lagrangian Acceleration (COLA) method. The lightcone is constructed in spherical shells from the source to...
Go to contribution page -
Ethan Milligan (QMUL)08/04/2025, 10:00UK CosmoTalk
In this work, we introduce a numerical code that solves the Misner-Sharp formalism for a spherically symmetric cosmological model containing both a scalar field and a perfect fluid. While the code is capable of exploring general scenarios involving an uncoupled scalar field and perfect fluid, our current research focuses on the regime where the scalar field dominates the dynamics. As an...
Go to contribution page -
Elena Colangeli (ICG - University of Portsmouth)08/04/2025, 10:50UK CosmoTalk
Further bright sirens -- gravitational wave events with electromagnetic counterparts -- are keenly awaited, but proving elusive. The exceptional event GW170817 had a profound impact on the landscape of viable cosmological extensions of General Relativity (GR); can we expect this kind of shift to be repeated in the next decade? In this work we will assess the potential constraints from bright...
Go to contribution page -
Nayeli Marisol Jimenez Cruz (Swansea University)08/04/2025, 11:10UK CosmoTalk
Recent Pulsar Timing Array (PTA) observations provide strong evidence for a stochastic gravitational wave background (SGWB), potentially originating from astrophysical sources or early universe phenomena. If the SGWB is cosmological, our relative motion with respect to the SGWB rest frame induces a kinematic anisotropy, which could dominate over intrinsic anisotropies, similar to the cosmic...
Go to contribution page -
Alisha Marriott-Best (Swansea University)08/04/2025, 11:30UK CosmoTalk
LISA and ET will operate in different frequency ranges but with comparable integrated sensitivities to a stochastic GW background (SGWB). We explore their synergies in detecting cosmological SGWBs with large amplitudes and broad frequency spectra, arising from sources such as cosmological phase transitions, cosmic strings, and primordial inflation. By combining measurements from both...
Go to contribution page -
Joonas Hirvonen (University of Nottingham)08/04/2025, 11:50UK CosmoTalk
Cosmological first-order phase transitions may have generated an observable gravitational wave background, offering a unique probe of beyond-Standard-Model physics. A crucial step in predicting this background is the reliable computation of bubble nucleation rates. In this talk, I will give an overview of recent advancements in perturbative high-temperature nucleation rate calculations. These...
Go to contribution page -
Dr Emine Şeyma Kutluk (Scuola Normale Superiore)08/04/2025, 15:50UK CosmoTalk
We write a closed form expression for the metric perturbation around de Sitter that describes gravitational radiation from a compact and slowly varying source, in terms of a consistent multipolar expansion at quadrupolar order. We show that the corresponding displacement memory effect with both the even and odd parities is at a higher order in the radial expansion compared to their flat...
Go to contribution page -
Trevor Cheung (University of Nottingham)08/04/2025, 16:10UK CosmoTalk
Primordial perturbations observed on the CMB are thought to come from cosmological correlators during inflation. While massive (spinning) fields lead to vanishing correlators, their interaction with massless ones can alter the massless field correlators. These changes can be used to infer existence of massive spinning fields during inflation. We will compare two main models of massive spinning...
Go to contribution page -
Andrea Costantini (Queen Mary University of London)08/04/2025, 16:30UK CosmoTalk
A key step in the comparison between inflationary predictions and cosmological observations resides in the computation of primordial correlators.
Go to contribution page
Numerical methods have been developed, which allow to overcome some of the difficulties arising in analytical calculations when the models considered are complex.
The \texttt{PyTransport} package, which implements the transport formalism, allows... -
Yuejia Zhai (University of Sheffield)08/04/2025, 16:50UK CosmoTalk
Although ΛCDM has been a successful cosmological model, there is a 5σ tension between $H_0$ values inferred from the cosmic microwave background (CMB) data by Planck and those measured directly by SH0ES. Apart from the Hubble tension, debates also extend to tensions on other cosmological parameters. Many alternative models are proposed to reconcile these tensions in cosmology. I will focus on...
Go to contribution page -
Prof. Adam Pound (University of Southampton)09/04/2025, 11:30Gravitational wavesTalk
Historically, studies of the merger stage of a black hole binary have centred on fully nonlinear numerical relativity simulations. However, nonlinear black hole perturbation theory provides powerful insights into the ringdown regime immediately following merger, and perturbative self-force theory has proved highly accurate in describing asymmetric binary inspirals even for mass ratios not too...
Go to contribution page -
Mr Ayush Roy (University of Southampton)09/04/2025, 11:50Gravitational wavesTalk
Gravitational self-force theory (GSF) has proved to be a viable method of solving the general relativistic 2-body problem for asymmetric binaries, with state-of-the-art GSF inspiral waveforms now exhibiting minimal phase error across all mass ratios smaller than ~1/10. Recent work has extended these GSF inspiral waveforms to include beyond-GR effects in a broad class of scalar-tensor theories....
Go to contribution page -
Guillermo Lara (Max Planck Institute for Gravitational Physics (Albert Einstein Institute))09/04/2025, 16:10Gravitational wavesTalk
In this talk, I will present recent developments aimed at simulating black hole binaries beyond general relativity in Spectre, an open-source numerical relativity code by the SXS Collaboration. For concreteness, I will focus on scalar Gauss-Bonnet (sGB) gravity. I describe results derived from a parameter space exploration of a model of sGB gravity using initial data sequences of equal-mass...
Go to contribution page -
Giovanni D'Addario (University of Nottingham)09/04/2025, 16:30Gravitational wavesTalk
Black hole quasi-normal modes (QNMs) provide a powerful probe of deviations from General Relativity. We analyze the relative contributions of shifts in the QNM spectrum of Kerr black holes and the presence of additional modes sourced by extra fields in a theory-agnostic framework. By exploring different regimes, we identify when each effect dominates and propose suitable ansätze for the...
Go to contribution page -
Patrik Svancara (University of Nottingham)10/04/2025, 10:00ExperimentsTalk
I will present a newly established, Nottingham-based experimental platform for simulating rotating curved spacetimes in superfluid helium - a quantum liquid with vanishing viscosity. The effective curved spacetime, induced by the most extensive quantum vortex flows ever created, is probed via micrometre-scale surface waves. These reveal intricate wave-vortex interactions, including the...
Go to contribution page -
Lodovico Capuano (Scuola Internazionale Superiore di Studi Avanzati)10/04/2025, 11:50Gravitational wavesTalk
The inaccurate modeling of the gravitational wave templates that are used for analysing gravitational wave signals can lead to a systematic bias in the parameter estimation. This inaccuracy can be related to the lack of terms in the waveform coming from fundamental physics or astrophysical environments or to some truncation in perturbation theory. This issue is going to be more relevant for...
Go to contribution page -
Sofie Ried (Univesity of Sheffield)10/04/2025, 17:10Fundamental physicsTalk
Black holes serve as key testing grounds for quantum gravity due to their singular nature and have been extensively studied in various quantum gravity approaches. In this talk, I apply the Henneaux-Teitelboim formulation of unimodular gravity to the symmetry-reduced Schwarzschild-(Anti-)de Sitter model. We perform a canonical quantization, leading to a Wheeler-DeWitt equation that takes the...
Go to contribution page -
Maria Jose Guzman (University of Tartu, Estonia)10/04/2025, 17:30MathematicsTalk
We present recent advancements in the 3+1 formalism within two reformulations of general relativity: the teleparallel equivalent of general relativity, and the symmetric teleparallel equivalent of general relativity. Both theories are based on the torsion and nonmetricity of a flat connection, respectively, and their Lagrangians are expressed in terms of the torsion scalar T and the...
Go to contribution page