IWARA2026 - 12th International Workshop on Astronomy and Relativistic Astrophysics

Contribution List

47. A mathematical construction of the 260-day mesoamerican calendar based on archaeoastronomical alignments

Sergio Mendoza

Talk

This work presents a formal mathematical and arithmetic framework for the construction of the ancient 260-day Mesoamerican ritual calendar. We demonstrate that the fundamental calendar relation (365×52=260×73) is a direct representation of Kepler's third law of orbital motion in synodic coordinates. Using a generalized definition of a short calendar count derived from symmetrical...

37. A natural explanation of the Galactic Magnetic Fields from multistate Scalar Field Dark Matter

Luis Bryan Mendoza Meza (Centro de Investigación y de Estudios Avanzados del Instiuto Politécnico Nacional)

Poster

In this work, we investigate the possibility that the large-scale magnetic fields
observed in galaxies, of the order of microgauss, arise naturally from a complex Scalar Field Dark Matter (SFDM) halo charged under a local U(1) symmetry. Extending our previous work, where multistate SFDM solutions were shown to form “gravitational atoms” capable of explaining the anisotropic distribution of...

26. A Practical Guide to ALP Analysis in Astrophysical Environments

Alvaro Pratts (IF-UNAM)

Talk

Axion-like particles (ALPs) represent well-motivated candidates for dark matter. However, searching for ALPs using very-high-energy (VHE) gamma-ray observations requires a multidisciplinary approach that is seldom addressed comprehensively in a single reference. In this work, we present a practical guide for researchers entering the field, outlining the essential steps to develop a robust...

16. A Stochastic Forward Model for the Dispersion Measure Distribution of Fast Radio Bursts

W. S. Hipolito-Ricaldi (Universidade Federal do Espírito Santo)

Talk

We present a stochastic forward framework for modeling the dispersion measure (DM) of Fast Radio Bursts. The intergalactic DM is formulated as a line-of-sight integral through a structured cosmic web, with fluctuations arising from stochastic encounters with halos and filaments. This naturally induces a full probability distribution P(DM∣z), capturing both the mean signal and the cosmic...

64. Beyond the Binary: A Quaternary Algebraic Framework for Inka Mathematics in the Yupana and Khipu

CESAR AUGUSTO Zen Vasconcellos (UFRGS/ICRANet)

Talk

abstract. The decipherment of Inka mathematics stands at a crossroads. Rojas-Gamarra and Stepanova (2015) proposed a positional, base-10 interpretation of the Yupana and Khipu. In contrast, Overmann and Florio (2025) argue for a non-positional, additive system based on the visual ambiguity of khipu knots. This paper resolves this contradiction by demonstrating that both interpretations capture...

59. Bondi-type accretion onto a Kerr black hole in the kinetic regime

Mehrab Momennia (Universidad Michoacana de San Nicolás de Hidalgo)

Talk

The dark matter-black hole interaction is modeled with the help of the accretion of a Vlasov gas into a rotating Kerr black hole. We provide exact analytic expressions for the particle, mass, and angular momentum accretion rates in the form of integrals. These integrals are computed numerically and compared to more explicit relations in the slow-rotation approximation. The explicit analytic...

39. Characterizing the multi-wavelength spectral energy distribution of radio galaxies up to TeV energies with HAWC

Mabel Osorio (IA-UNAM)

Talk

The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field water Cherenkov detector (WCD) that continuously monitors the gamma-ray sky in the energy range from hundreds of GeV to beyond 100 TeV. After nine years of observations, spanning from 2015 to 2024, HAWC provides measurements on four radio galaxies in the northern hemisphere known to emit at very-high-energy (VHE) gamma rays....

15. Combined constraints on dark photons from high-energy collisions, cosmology, and astrophysics

Adrian William Romero Jorge (Frankfurt Institute for Advanced Studies/Goethe University Frankfurt)

Talk

We investigate a dark sector coupled to the Standard Model (SM) through a kinetically mixed dark photon $U$ associated with a new $U(1)'$ gauge symmetry. Kinetic mixing, parametrized by $\varepsilon$, induces an effective coupling to the electromagnetic current, while the dark photon interacts with a stable dark matter (DM) particle $\chi$ through a dark gauge coupling $g_\chi$, defining a...

55. Constraining a model supported in Moiré gravity

Jesús Astorga-Moreno (Cinvestav)

Poster

Moiré theory is a revolutionary alternative arising from solid-state physics that can be extended to gravity, forming a framework called Moiré gravity. The idea behind it is that Einsteinian gravity has a validity limit and must be extended to Moiré gravity, in which the Friedmann equation changes and a new scalar field emerges. In this vein, in this paper, we propose an analytic solution for...

28. Constrains on Axion-Like Particles from Gamma-Ray Spectral Irregularities in the Crab Nebula

Mauricio Ordoñez-Tehozol (UNAM)

Poster

Axion-like particles (ALPs), predicted in extensions of the Standard Model, arise as candidates for cold dark matter. Their coupling to photons in external magnetic fields leads to photon–ALP oscillations, which can affect the propagation of very-high energy gamma rays over astrophysical distances. Such effects may manifest as energy dependent distortions and small-scale irregularities in the...

31. Constraints on Axion-Like Particles from HAWC Observations of M87

José Serna (Instituto de Física - Universidad Nacional Autónoma de México)

Talk

We present constraints axion-like particles (ALPs) derived from 7.5 years of very-high-energy gamma-ray observations of the radio galaxy M87 with the High Altitude Water Cherenkov (HAWC) Observatory. ALPs are well-motivated dark matter candidates that can oscillate into photons in the presence of external magnetic fields — a phenomenon known as photon–ALP conversion — potentially producing...

29. Constrictions for ALPs as Dark Matter Candidates with the quasar 3C 273 though Fermi-LAT data

Luis Damián Anaya Martínez (Instituto de Física, Universidad Nacional Autónoma de México)

Talk

Dark matter constitutes approximately 27% of the total energy content of the Universe, making its nature one of the most important open questions in modern physics. Among the proposed dark matter candidates are Axion-Like Particles (ALPs), hypothetical particles that can couple to photons and undergo photon–ALP oscillations in the presence of magnetic fields over astrophysical distances....

19. Constructing de Sitter space and Dark Matter with Dynamical Tension Strings

Eduardo Leon Guendelman (Ben Gurion University)

Talk

The string tensions can be dynamical in the modified measure formalism and appear as an additional dynamical degrees of freedom . These tensions may not be universal, instead, each string generates its own tension. We then consider a new bulk field that can couple to the strings, the tension scalar which changes locally the tension along the world sheet. In the case with two string tensions...

54. Cosmology on a gravitational-wave background

Claudio Salas Pérez (CINVESTAV)

Poster

The hypothesis that the Universe is permeated by a cosmological background of gravitational waves has gained increasing interest in theoretical cosmology. In this context, the CMaDE model proposes that dark energy can be understood as a dynamical contribution associated with the gravitational-wave background, whose characteristic scale is linked to the cosmological evolution of the horizon. In...

21. Curvature invariants and trace anomaly in neutron stars

Iván Hernández Garibay (Goethe University Frankfurt)

Talk

Understanding the extreme conditions inside neutron stars represents a
major challenge for Astrophysics. Here I present our investigation on
the behaviour of curvature invariants for a large ensemble
of neutron stars built with equations of state (EOSs) that satisfy
constraints from nuclear theory and perturbative QCD, as well as
measurements of neutron-star masses, radii, and...

13. Dark Matter Content of Gas Rich Dwarf Galaxies

OWEN BEUKES (North West University)

Talk

Using high resolution RSS longslit data recently obtained from SALT, we have obtained the mass distribution in a nearby gas-rich dwarf galaxy - UGCA 014. In this talk, I will present the first rotation curve for this galaxy derived from its Hβ ionized gas component. I will show that the rotation curve exhibits a steep rise in the inner kiloparsec, reaching a velocity of ∼42 km/s, and remains...

9. Deformed phase-space for a non-singular cosmology

Dr ERI ATAHUALPA MENA BARBOZA (Centro Universitario de la Ciénega, Universidad de Guadalajara)

Talk

We present the implications of incorporating noncommutativity into f(R) gravity. In particular, we explore the proposed framework in a flat FRLW background. We introduced a deformation in a 2n-dimensional phase space.

12. Deriving Exoplanets’ Structural and Dynamical Properties from Mass-Radius Relations: Linking Composition, Spin and Atmospheric Parameters

Rifah Anjum Priti (University of Rajshahi)

Poster

The mass-radius relationship of exoplanets provides a fundamental connection between their observable characteristics and internal structure. In this study, we develop a comprehensive framework in order to derive key planetary parameters, including surface gravity, mean density, escape velocity, moment of inertia, spin period and atmospheric scale height, directly from mass and radius...

5. Disentangling Stellar Mass and Environmental Effects on AGN activity

Navya Saraswat (Tata Institute of Fundamental Research)

Talk

We investigate the environmental dependence of active galactic nucleus (AGN) activity using a stellar mass-complete sample of 36,000 galaxies from the Galaxy and Mass Assembly (GAMA) survey overlapping with the eROSITA Final Equatorial Depth Survey (eFEDS) field. By combining
X-ray observations from eROSITA, optical and infrared photometry from Legacy Survey and WISE, UV data from GALEX, and...

6. Disk, Corona, and Jets: A Unified UV–X-ray Perspective on Black Hole Binaries

Prof. Samir Mandal (Indian Institute of Space Science & Technology)

Poster

Accretion onto stellar-mass black holes in X-ray binaries produces diverse spectral and temporal behaviour across the electromagnetic spectrum. The ultraviolet (UV) and X-ray bands are particularly powerful diagnostics, directly probing the outer accretion disk, the hot inner flow and corona, and disk–wind interactions.

In this work, we present a comprehensive UV–X-ray spectral study of...

71. Dissipation in charged gases: transport properties for the simple gas and binary mixtures

Ana Laura García-Perciante (Universidad Autónoma Metropolitana)

Talk

Relativistic fluid theories derived from kinetic theory provide a consistent framework for describing transport processes in out-of-equilibrium systems. In this context, first-order perturbative solutions of the relativistic Boltzmann equation lead to constitutive equations that couple dissipative fluxes to both spatial and temporal derivatives of the state variables, as well as to the...

35. DM-induced relics in galaxy clusters

Sergio Hernández Cadena (SJTU)

Talk

Galaxy clusters are the largest gravitationally-bounded systems in the Universe. In these objects, the dark matter (DM) represents almost 85% of their content, while ~5% are galaxies and the rest corresponds to hot gas filling the Intra Cluster Medium (ICM). If the DM is a heavy particle like the Weakly Interactive Massive Particles (WIMPs), galaxy clusters are exceptional targets to...

24. Dynamical stability properties of these charged Proca stars

Jorge Yahir Mio Pacherre (Instituto de Ciencias Nucleares UNAM)

Poster

We study the dynamical stability properties of these charged Proca stars (constructed in Mio and Alcubierre,2025) by adding a small but finite perturbation to the original stationary configurations, and then performing numerical evolutions while keeping the spherical symmetry. We show that, for any given family, the parameter space can be separated into three regions corresponding to...

33. Emergence of a $1/r$ Gravitational Regime from a Corrected Relativistic Structure

Frederic Lassiaille

Talk

We present recent developments of a corrected relativistic framework based on a structural re-examination of the spacetime–energy coupling in General Relativity. The approach replaces the standard static description of matter with a fully dynamical representation of energy, leading to additional first-order structural contributions in the Einsteinian formulation.

A recent technical advance...

62. Equilibrium of magnetized accretion tori around Kerr black holes

Juan Zaldívar (INAOE)

Talk

Magnetized equilibrium accretion discs are the standard initial condition for general-relativistic magnetohydrodynamic (GRMHD) simulations of black-hole accretion, including those used to interpret Event Horizon Telescope images of M87 and Sgr A. These configurations are stationary by construction and are therefore commonly assumed to be straightforward to evolve numerically. Using the BHAC...

65. Existence of non-relativistic rotating boson stars: A variational approach.

Emmanuel Chávez Nambo (Universidad Michoacana de San Nicolás de Hidalgo)

Talk

In this talk, we will present the rigorous proof of existence of ground states for the Schrödinger-Poisson system, which model rotating boson stars. The model reduces to minimizing an energy functional under an ansatz with $SO(2)$ symmetry.
The main analytical challenge is the loss of compactness typical of Sobolev embeddings in $\mathbb{R}^3$. Using the concentration-compactness principle,...

56. Fake shadows of stable non-ultracompact objects

Hector Olivares (Universidade de Aveiro)

Talk

The image of a black hole (BH) in an optically thin environment is expected to be characterized by a dark central region surrounded by a bright ring of a characteristic size. The BH shadow and the photon ring are believed to play an important role in producing these features, both of which are observed in horizon-scale images of supermassive BH candidates. In this talk, we show that a...

45. From Photon Energy to Thermal Telescopes: A New Theoretical Approach

Prof. Gh. Saleh (Saleh Research Centre)

Poster

This paper presents an alternative interpretation of photon energy differences within the framework of Saleh Theory and proposes a thermal approach for spectral detection. Unlike the conventional view that relates photon energy directly to frequency through Planck’s equation, this work focuses on a physical explanation based on differences in photon trajectories.

The theory assumes that...

46. Galactic dynamics from pure torsion

Sergio Mendoza

Talk

I present a relativistic modified gravity theory based on a scalar function of the torsion tensor. In the weak-field limit, the field equations naturally reduce to the deep-MOND regime without introducing dark matter. This framework simultaneously reproduces the observed deflection of light across individual galaxies and clusters, and yields an exact derivation of the baryonic Tully-Fisher...

2. Geometry-first inference for megamaser disks: finite-distance Gauss--Bonnet emission mapping in static spherically symmetric spacetimes

Santiago González Salud (Faculty of Physical and Mathematical Sciences - Benemérita Autonomous University of Puebla)

Talk

Water H$_2$O megamasers in sub-parsec circumnuclear disks provide geometric constraints from VLBI sky positions, line-of-sight frequency shifts $z$, and---when monitored---their secular drifts. We present a geometry-first forward model for equatorial maser disks in a generic static, spherically symmetric (SSS) spacetime written in Schwarzschild gauge. The construction is formulated on the...

14. Gravitational Waves from Mergers of Asymmetric Dark Stars

Boris Betancourt Kamenetskaia (Institute for Basic Science CTPU-CGA)

Talk

A strongly self-interacting component of asymmetric dark matter (DM) particles can form compact dark stars (DSs). These objects have a broad spectrum of masses and radii, with distinct evolution histories from both neutron stars and black holes (BHs). We argue that these differences allow a population of DSs to contribute significantly to the astrophysical merger rate in unique and discernible...

18. GW Bispectra: A Novel Window on Gravity.

Nayeli Marisol Jimenez Cruz (Swansea University)

Talk

This is a new test of modified gravity using gravitational-wave experiments, based on three-point correlation functions of the stochastic gravitational-wave background. While standard analyses focus on tensor polarisations predicted by General Relativity, many alternative theories allow additional scalar modes. We show that bispectrum-based observables provide a robust way to isolate these...

25. Identifying Galaxy Glusters in Redshift Space with Machine Learning

Greco Peña (Universidad de Valparaíso)

Talk

Galaxy clusters are key tracers of the large-scale structure of the Universe and powerful probes of cosmology. However, identifying clusters directly in redshift space remains challenging because peculiar velocities distort their apparent distribution, producing anisotropic structures such as Finger-of-God elongations and coherent infall. In this talk, I will present preliminary results from a...

51. Implementation of Profile Likelihood approach for cosmological parameter estimation in SimpleMC

Valeria Herrera Tinoco (Instituto de Ciencias Físicas- UNAM)

Poster

This work aims to implement likelihood profile techniques within the SimpleMC framework as a frequentist approach to cosmological parameter estimation. The method consists of fixing a parameter of interest while doing MLE with respect to the remaining free parameters, allowing the construction of one-dimensional likelihood profiles. To improve the efficiency of the parameter exploration,...

1. Inclination-induced apparent warping in megamaser disks: a non-equatorial Gauss--Bonnet framework for VLBI data

Santiago González Salud (Faculty of Physical and Mathematical Sciences - Benemérita Autonomous University of Puebla)

Poster

VLBI maps of H$_2$O megamaser disks often display a curved (``warped-looking'') locus of maser spots on the sky. We show that such a morphology can arise as a purely geometric projection effect, without invoking an intrinsically warped disk. To this end we develop a non-equatorial, finite-distance Gauss--Bonnet construction for null-ray propagation in a general static, spherically symmetric...

48. Long-term VHE Variability of Mrk 421 and Mrk 501: A Decade of HAWC Observations

Erick Alejandro Rangel (Instituto de Astronomía, UNAM)

Talk

The High-Altitude Water Cherenkov (HAWC) Observatory is located on the slopes of Sierra Negra volcano in Mexico at an altitude of 4,100 m above sea level. HAWC is a wide-field-of-view detector designed to observe very-high-energy (VHE) gamma rays in the energy range from hundreds of GeV to beyond 100 TeV, while operating with a duty cycle greater than 95%. Since the start of full operations in...

4. Lya2pcf: an efficient pipeline to estimate two- and three-point correlation functions of the Lyman-α forest

Rafael Gutiérrez Balboa (Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional)

Poster

Studying the matter distribution in the universe through the Lyman-α forest allows us to constrain small-scale physics in the high-redshift regime. Spectroscopic quasar surveys are generating increasingly large datasets that require efficient algorithms to compute correlation functions. Moreover, cosmological analyses based on Lyman-α forests can significantly benefit from incorporating...

27. Neutrino Production Rate Calculations Using Monte Carlo Integration Methods

Eder Leoni López (UNAM)

Poster

Once a massive star exhausts its nuclear fuel, the core collapses under its own gravity leading to the ejection of matter and, eventually, to the formation of a compact object known as a proto-neutron star. Under the extreme conditions (pressure, temperature, density), particle production through weak-interaction processes is favored, mainly via the direct Urca process, which results in the...

52. Neutrino transport in 1D relativistic stellar core collapse

Omar Elias Velasco-Castillo (Universidad Nacional Automoma de Mexico)

Talk

Type II supernovae explosions are one of the most energetic outflows in the Universe. The neutrino driven collapse of the iron core of supergiant stars is regarded as the most efficient mechanism for explaining the high luminosities in these events. In this talk, we will discuss two different scenarios after the collapse. The first one is a failed supernova forming a proto neutron star that...

30. Neutron Stars consistent Equations of State with Phase Transitions and their Impact in Heavy Ion Collisions Observables

Daniel Lluis Gonzalez (Goethe University Frankfurt)

Poster

We explore the impact of the equation of state (EoS) on heavy-ion collision observables using a Chiral Mean Field (CMF) framework constrained by astrophysical and lattice-QCD inputs. By varying the relative vector and scalar–vector couplings of $\Delta$ resonances and the scalar $\sigma$ field with respect to nucleons, we identify a family of EoS that simultaneously reproduce neutron stars...

34. Orbital and Thermodynamic Evolution of Inner Planets During the Solar Red Giant Phase

Amritpal Singh Nafria (Lamrin Tech Skills University)

Poster

As the Sun advances toward the red giant branch, secular changes in luminosity, mass loss, and tidal interactions will progressively reshape the inner solar system. The innermost terrestrial planet, subject to orbital decay and thermal runaways, will experience conditions incompatible with structural integrity. This event precipitates a realignment of orbital and thermal states among the...

43. Parameter estimation of generalized Ghosh black holes using shadow observables and Event Horizon Telescope Constraints

Himanshi Gulia (Netaji subhash university of technology)

Poster

The Event Horizon Telescope images of M87 and Sgr A give us a unique chance to test gravity in the strong field regime and assess deviations from the Kerr solution. We study the shadows of rotating nonsingular black holes—namely, generalized Ghosh black holes (GGBHs), given by the mass function $m(r) = M e^{-(k/r)^n}$, which reduces to the Kerr black hole ($k \to 0$) and to the original...

42. Phase Transitions in Magnetars: A Density-Dependent Approach

Cynthia Ahiezer Vizcarra Ventura (Universidad Continental)

Talk

Magnetars are natural laboratories to study matter under very strong magnetic fields at high densities. These extreme fields can modify the microscopic structure of matter by incorporating the idea of the Landau levels, which immediately the equations of state possibly triggering a phase transitions at the stellar cores. However, a full understanding of the interaction between magnetic fields...

50. Probing Neutron-to-Dark-Matter Conversion with Multimessenger Neutron-Star Observations

Hamidreza Moshfegh (University of Tehran)

Talk

Neutron stars provide a unique astrophysical laboratory for probing dark matter under extreme density and strong gravity. Motivated by dark-sector interpretations of the neutron lifetime anomaly, we investigate neutron-to-dark-matter conversion in dense neutron-star matter and its impact on the equation of state and stellar observables.

We model baryonic matter within a non-linear...

11. Probing white dwarf interiors with gravitational waves

Ethan Carlier (Université Libre de Bruxelles)

Poster

White dwarfs offer a unique laboratory for studying matter under strongly coupled and partially degenerate conditions. With the upcoming space‑based gravitational‑wave detectors, such as LISA, binary white dwarfs will become a major source of continuous gravitational‑wave signals. These observations will open a new window onto the internal physics of white dwarfs, providing access to...

38. Quantitative VHE Transient Detection Prospects for the Southern Wide-field Gamma-ray Observatory

Pedro Elías Mirón Enríquez (Instituto de Astronomía, UNAM)

Talk

We present a systematic and quantitative assessment of the Southern Wide-field Gamma-ray Observatory's (SWGO) detection rates for very-high-energy (VHE; >100 GeV) transient sources. Using the SWGO instrument response functions — including effective area, background rates, and point-spread function across three zenith-angle bands and three core-distance bands — we construct spectral templates...

44. Quantitative VHE Transient Detection Prospects for the Southern Wide-field Gamma-ray Observatory

Pedro Elías Mirón Enríquez (Instituto de Astronomía, UNAM)

Talk

We present a systematic and quantitative assessment of the Southern Wide-field Gamma-ray Observatory's (SWGO) detection rates for very-high-energy (VHE; >100 GeV) transient sources. Using the SWGO instrument response functions — including effective area, background rates, and point-spread function across three zenith-angle bands and three core-distance bands — we construct spectral templates...

57. Relativistic Bondi–Hoyle–Lyttelton Accretion with Realistic Equations of State in HUASTECO code.

Rodrigo Anaya (Instituto de Astronomía, Universidad Nacional Autónoma de México)

Talk

Title: Relativistic Accretion with a Realistic Equation of State using HUASTECO code.

Abstract: We present relativistic Bondi--Hoyle--Lyttleton accretion with realistic equations of state using the HUASTECO code. The system consists of a black hole moving supersonically
through a gaseous medium, forming an accretion shock cone. The main goal is to study more realistic accretion scenarios...

58. Relativistic dissipative fluids from kinetic theory using the trace-fixed particle frame

Olivier Sarbach (Universidad Michoacana de San Nicolás de Hidalgo)

Talk

We discuss a new dissipative fluid theory on an arbitrary (flat or curved) spacetime background. This theory is obtained from kinetic theory by applying a new version of the relativistic Chapman-Enskog method to derive the constitutive relations to first order in the Knudsen parameter. The novelty of our approach consists in applying a suitable projection method to solve the linearized...

61. Relativistic Dissipative Fluids in the Trace-Fixed Particle Frame

Dr Félix Salazar (Universidad Autónoma Metropolitana (UAM))

Talk

In this talk, we present a first-order theory of relativistic dissipative fluids formulated in the trace-fixed particle frame; a variant of Eckart's frame in which the temperature is determined by fixing the trace of the stress-energy tensor. We show that the resulting theory is hyperbolic and causal provided that a single inequality is satisfied. We also prove that global equilibrium states...

49. Relativistic tidal separation of binary stars by supermassive black holes

Emilio Tejeda (Instituto de Física y Matemáticas, UMSNH)

Talk

We present the Hybrid Relativistic-Newtonian Approximation (HRNA), a novel and computationally efficient framework designed to simulate the dynamics of self-gravitating systems orbiting within a fixed, curved background spacetime. The HRNA operates at the intersection of two physical regimes: the global motion follows exact general relativistic geodesics in a black hole metric, while the...

3. Reparametrization Invariance and the Phenomena of Dark Energy & Dark Matter

Dr Vesselin Gueorguiev (NCIS, RIIS 2.0, and IAPS)

Talk

The nature of dark energy (DE) challenges our comprehension of the cosmos, appearing as the source responsible for the Universe’s accelerating expansion. This work considers the Einstein Cosmological Constant (ΛE) as a manifestation of DE, interpreted through the lens of Reparametrization Invariant Scaling Symmetry (RISS). Within this paradigm, ΛE emerges as a “kinetic energy” term, derived...

32. Representations of Spacetime: From Kruskal Coordinates and Stereographic Projections to Causal Diamonds and the Golden representation

Edgar Alejandro León Espinoza (Universidad Autónoma de Sinaloa)

Talk

We start by examining the relations between the Kruskal representation and stereographic projection. Motivated by novel results in spherically-symmetric metrics, we explore the analogue of conformal-Minkowski mappings. To this end, we introduce 'Diamond Coordinates,' a compactified representation that naturally delineates local causal diamonds. By analyzing the worldlines of observers within...

20. Revisiting Peculiar Velocities with General Relativity

Sebastián Nájera (ICF UNAM)

Talk

We present a fully relativistic treatment of cosmological peculiar velocities within General Relativity, moving beyond the standard Newtonian approximation commonly employed in large-scale structure studies. Peculiar velocity fields are derived from analytic solutions of Einstein’s equations sourced by non-perfect fluids and interpreted through frame transformations with respect to a...

60. Revisiting Quadratic Scalar Field (Fuzzy, Wave, Ultralight) Dark Matter in Light of DESI DR2 and Current Cosmological Observations

Muhammad Awais (ESFM - Escuela Superior de Física y Matemáticas - IPN)

Poster

We investigate the cosmological viability of quadratic scalar field dark matter (SFDM), also known as fuzzy, wave, or ultralight dark matter, where the dark matter sector is modeled as a single ultra-light scalar field with potential
[
V(\phi)=\frac{1}{2}m_\phi^2\phi^2 .
]
The scalar-field background evolution and linear perturbations are implemented in a modified version of the...

41. Search for delayed and extended TeV gamma ray emission in long GRBs

Alexis Andrés (IA-UNAM)

Talk

Gamma-ray bursts (GRBs) are among the most energetic phenomena in the Universe. Their emission typically consists of a brief prompt phase observed in the sub-MeV energy range, followed by a delayed and longer-lasting afterglow detected across the electromagnetic spectrum. In a few cases, GRB afterglows have also been observed at TeV energies, from minutes to several hours after the trigger...

53. Signatures of Blandford-Znajek mechanism in M87 jet

Alejandro Cruz Osorio (Goethe University)

Talk

Relativistic jets are launched in the immediate vicinity of black holes and emit radiation across the entire electromagnetic spectrum. According to our current understanding, these powerful outflows are driven by extracting rotational energy from spinning black holes via the Blandford–Znajek mechanism. Numerical simulations have further demonstrated that the accumulation of magnetic flux onto...

66. Singularity Resolution in Anisotropic Quantum Gravity: Unifying Horava- Lifshitz Dynamics

CESAR AUGUSTO Zen Vasconcellos (UFRGS/ICRANet)

Talk

abstract. Spacetime singularities represent fundamental limitations of classical gravity that require quantum resolution. We develop a dual geometric-dynamical framework combining: (1) anisotropic scaling for ultraviolet completeness and (2) pseudocomplex geometry for singularity resolution. This unified approach achieves simultaneous renormalizability, geodesic completeness, and unitary...

69. Surrogate Modeling of Very High-Energy GRB Afterglows Using Artificial Neural Networks

Dr Edilberto Aguilar Ruiz (Instituto de Radioastronomía y Astrofísica, UNAM)

Talk

Recent detections of very high-energy (VHE; $E > 100$\,GeV) emission from gamma-ray burst (GRB) afterglows have highlighted the need for accurate synchrotron self-Compton (SSC) models. Although numerical approaches provide a realistic description of the underlying radiation processes, their high computational cost makes them impractical for conventional parameter estimation methods such as...

67. The 500 m Precision Floor in Neutron Star Radius Measurements

CESAR AUGUSTO Zen Vasconcellos (UFRGS/ICRANet)

Talk

abstract. Multi-messenger observations of neutron stars aim to constrain the dense-matter equation of state via mass-radius measurements. We demonstrate that, for a canonical 1.4 M⊙ star, current crust-modeling uncertainties impose a persistent∼500 m precision floor in radius predictions. This threshold is comparable to—and in some cases exceeds—the radius differences predicted for...

8. The Euclid survey

Xavier Dupac (European Space Agency)

Talk

Euclid is European Space Agency’s space telescope dedicated to cosmology, through two main probes: weak lensing and galaxy clustering. It was launched in July 2023 and is now in its third year of survey. It is performing a large photometric and spectroscopic survey of galaxies over 14000 sq. deg. of the Extragalactic sky (Wide Survey), as well as a Deep Survey of three areas of the sky (53 sq....

17. The pseudo-complex FLRW model and the time evolution of the Hubble parameter

Prof. Cesar Augusto Zen Vasconcellos (ICRANet), Prof. Fridolin Weber (University of California at San Diego), Leila Maghlaoui (Mentouri Univeristy), Peter Hess

Talk

The pseudo-complex version of the Friedmann–Lemaître–Robertson–
Walker model (pcFLRW) is presented within the framework of pseudo-complex
General Relativity (pcGR). In this approach, dark energy arises as a geometric
consequence of the pseudo-complex structure, leading to a time-dependent
Hubble parameter H(z), which at the present time yields a value H0 and, crucially,
a non-zero time...

63. The Topological Horizon of Chankillo: How a Pre-Inca Civilization Encoded the Solar Cycle in Stone

CESAR AUGUSTO Zen Vasconcellos (UFRGS/ICRANet)

Talk

abstract. The Thirteen Towers of Chankillo (fourth century B.C.E., coastal Peru) form a calibrated solar observatory whose visual span of 47◦ exactly matches the Sun’s annual declination range. This correspondence is not a coincidence of natural topography but the result of deliberate architectural design: the towers are positioned along a gently curving ridge at a fixed distance of...

10. Tidal deformations of neutron stars: role of superfluidity and temperature

Ethan Carlier (Université Libre de Bruxelles)

Talk

The observation of the gravitational-wave signal GW170817 from a binary neutron-star merger marked the beginning of a new era in astrophysics. Such events offer unique opportunities to probe the properties of matter under conditions so extreme that they cannot be reproduced in terrestrial laboratories. During the inspiral phase, neutron stars undergo slight deformations induced by the tidal...

36. Vacuum-Remnant Dark Matter from Collapsed Vacuum Bubbles in a Three-Form Gauge Sector

Muhammad Ghulam Khuwajah Khan (Indian Institute of Technology, Jodhpur)

Poster

The microscopic identity of dark matter and the smallness of the observed vacuum energy remain two central puzzles in cosmology. I present a framework in which both questions are tied to a single additional gauge sector. In four spacetime dimensions, a three-form gauge field has a four-form field strength with no local propagating degrees of freedom. Instead, it labels distinct vacuum-energy...

68. VPOS from multistate Scalar Field Dark Matter

Tula Bernal (Universidad Autónoma Chapingo)

Talk

Observations have confirmed that satellite galaxies of the Milky Way, as well as those of Andromeda and Centaurus A, exhibit a non-homogeneous distribution known as the Vast Polar Structure (VPOS), where satellites show orbits aligned perpendicular to the host galaxy's plane. Conventional Cold Dark Matter (CDM) models face significant challenges in explaining this anisotropic distribution...

7. Why pressure fails as the matter Lagrangian of an ideal fluid

Sarahí Silva García (Universidad Nacional Autónoma de México)

Poster

In this work, we demonstrate that identifying the matter Lagrangian with the pressure leads to physical inconsistencies, which are resolved when the fluid is coupled to the gravitational field. In such a scenario, the matter Lagrangian necessarily assumes the value ofthe total energy density. We thus conclude that, for an ideal fluid, the only physically consistent choice for the matter...