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Jhan Nicolás Martínez Lobo (Universidad Industrial de Santander)05/11/2026, 09:00
Lovelock’s hypotheses are a set of reasonable conditions one can impose on the gravitational action that hugely narrow the set of possible gravity theories. In four dimensions, and for a Lorentzian space-time manifold, the set of gravity theories reduces to just one: General Relativity. This incarnation of the Ockham’s razor philosophy has influenced in one way or another the research on the...
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David Ricardo Moreno Diaz (Universidad Industrial de Santander)05/11/2026, 10:00
We study the cosmological dynamics of a general class of models where bulk viscosity is a property of dark matter using a dynamical system analysis. These viscous cosmologies are characterized by a dimensionless bulk viscous pressure given by $\Omega_\Pi = \Omega_\Pi(\Omega_m)$, where $\Omega_m$ is the matter density parameter. This phase-space analysis suggests that, in an Eckart framework, a...
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Holman Quintero-Salazar (Universidad de Guanajuato)05/11/2026, 10:30
We recalibrate the anchor sample of the L–σ relation for HII Galaxies (HIIG), an independent three-rung distance estimator that uses Giant Extragalactic HII Regions (GEHR) as local anchors. GEHR and HIIG are blue massive starburst systems that exhibit a seemingly ubiquitous correlation between their H-beta (Balmer) luminosity and their spectroscopic velocity dispersion, known as the L-σ...
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Diego Gallego (Universidad Pedagógica y Tecnológica de Colombia.)05/11/2026, 11:20
Early matter-dominated epochs and non-standard cosmological scenarios are frequently motivated by top-down constructions and UV completions of beyond-Standard Model physics. Scalar fields, as natural extensions to the Standard Model of particles, provide a well-studied framework for exploring deviations from the concordance cosmological model and might play a crucial role in dark matter...
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Sebastián Moreno Chalacá (Universidad del Valle)05/11/2026, 11:50
A central question in quantum gravity is how the entropy of a black hole arises from its microstates. In string theory, individual microstates of D1-D5-P black holes are described by smooth, horizonless geometries known as superstrata, and holographic complexity offers a new tool to probe how these states differ from the black hole they build.
We compute the volume complexity (CV) of...
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10. Cosmology Cartography: estimación de redshift por píxel en imágenes HSC-SSP mediante redes U-NetJuan Camilo Sanchez Tovar (Universidad Nacional de Colombia)05/11/2026, 14:00
Los redshifts fotométricos suelen estimarse objeto por objeto, a partir de catálogos que dependen de la detección y segmentación previa de fuentes. En este trabajo se presenta un enfoque alternativo que predice el redshift directamente a nivel de píxel a partir de imágenes multibanda, con el fin de construir mapas densos de redshift del cielo. Para ese objetivo se utilizó zscrape, un pipeline...
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SANTIAGO GARCIA SERNA05/11/2026, 14:30
The quasi-static (QSA) and sub-horizon (SHA) approximations are standard tools used to simplify the complex dynamics of linear cosmological perturbations in modified gravity. However, their conventional implementation relies on an ad-hoc truncation of time derivatives, which obscures theoretical errors and inadvertently eliminates fundamental background dynamics. In this work, we propose a...
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Dr Chandra B. Singh05/11/2026, 15:00
The discovery of quasars and their supermassive black holes (SMBHs) over $10^{9}$ $M_{\odot}$ merely hundreds of millions of years after the Big Bang generates tension with the idea of Eddington-limited accretion and pressures the community into exploring the concept of massive black hole seeds and/or super-Eddington accretion. The observation that many black holes have reached supermassive...
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Yeinzon Rodríguez García05/11/2026, 15:50
Three decades ago, Ted Jacobson surprised us with a very appealing approach to classical gravity. According to him, the gravitational field equations are the consequence of the first law of thermodynamics applied to a Rindler observer. Jacobson’s approach, being formulated for Riemannian geometries, we have wondered what its consequences would be for non-Riemannian geometries. The results of...
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JOHN BAYRON ORJUELA-QUINTANA (UNIVERSIDAD DEL VALLE)05/11/2026, 16:20
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...
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Mr Jose Palacios-Cordoba (Universidad del Valle)05/11/2026, 16:50
Although $\Lambda$CDM remains the standard cosmological model, outstanding observational and theoretical challenges motivate the exploration of alternative scenarios. Among these are models in which an anisotropic dark energy component breaks cosmic isotropy. In this talk, we investigate four classes of anisotropic dark energy models: a scalar field coupled to a vector field, a scalar field...
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Mr PEDRO MARTIN IBARBO PERLAZA (Universidad del Valle)05/11/2026, 17:20
La conjetura de la gravedad termodinámica establece que las ecuaciones de campo de la relatividad general pueden derivarse a partir de relaciones termodinámicas aplicadas al horizonte cosmológico. En este marco, la primera ley de la termodinámica aplicada al horizonte aparente de un universo plano y homogéneo descrito por la métrica FLRW permite obtener ecuaciones de Friedmann modificadas cuya...
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Dr Carlos Eduardo Cedeño Montaña (Universidad Santiago de Cali)06/11/2026, 09:00
From the field equations in the linear regime of the characteristic formulation of general relativity, Bishop, for a Schwarzschild’s background, and Mädler, for a Minkowski’s background, were able to show that it is possible to derive a fourth order ordinary differential equation, called master equation, for the J metric variable of the Bondi-Sachs metric. Once β, another Bondi-Sachs...
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Angeline Jolie Betancourt Beltran (Universidad el Bosque)06/11/2026, 10:00
Modern cosmology is grounded in the solution of the cosmological background equations, a system of differential equations obtained by applying Einstein’s field equations to a homogeneous and isotropic Universe. These equations describe the large-scale evolution of the Universe and form the basis of modern cosmological models and the interpretation of observational data. Although analytical...
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Sebastian Rueda Blanco (Universidad Nacional de Colombia)06/11/2026, 10:301
Active Galactic Nuclei (AGNs) are among the few astrophysical populations capable of probing the expansion history of the Universe beyond the redshift range currently accessible to Type Ia supernovae. We investigate their cosmological potential through an analysis of more than $5\times10^{5}$ quasars from the SDSS DR14 catalog spanning redshifts up to $z\sim3.5$. The ultraviolet--X-ray...
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Daniel Barrera (Universidad Nacional de Colombia - Sede Bogotá), David García Prieto (Universidad Nacional de Colombia)06/11/2026, 11:201
In this work we construct a fiber bundle for Dirac spinors associated with the orthogonal frame bundle using a spinorial representation of the Lorentz group. From this geometric framework, we derive an expression for the spin connection and formulate the general covariant Dirac equation in curved spacetime (gravitational background). Finally, we specialize to a FRW metric in conformal time to...
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Diego Fernando Fonseca Moreno (Universidad Nacional de Colombia/Universidad Antonio Nariño)06/11/2026, 11:50
Cosmological perturbation theory provides the fundamental framework for
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describing the evolution of the matter-energy density field in an expanding Universe and serves as the basis for understanding the formation of large-scale structures within the ΛCDM paradigm. In this work, we present a semi-analytical approach to describe the evolution of fluctuations —small deviations from the mean... -
Daniel Molano (Universidad de los Andes)06/11/2026, 14:00
Understanding how higher-order curvature corrections modify black hole spacetimes is essential for exploring possible deviations from General Relativity in the strong-field regime. In this work, we investigate the gravitational effects of a power-law Gauss–Bonnet modification in four dimensions, focusing on the perturbative structure of static, spherically symmetric vacuum solutions. Starting...
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Andrés Fernando Castillo Ramirez (Universidad Antonio Nariño)06/11/2026, 14:30
We present a geometric approach to the quantization of gauged nonlinear sigma models associated with the symmetry-breaking pattern $O(N+1)\to O(N)$, whose Goldstone fields parametrize the sphere $S^N\simeq O(N+1)/O(N)$. Starting from the linear sigma model, we describe the resulting nonlinear theory and gauge its $O(N)$ subgroup using Killing vector fields and differential forms on $S^N$. This...
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Cristian Eduardo Martínez Torres06/11/2026, 15:00
We present a study of the cosmic stability of a scalar dark matter candidate coupled to a pair of Majorana fermions using the Boltzmann equations. We incorporate quantum interactions, such as decay and annihilation processes into the evolution of the number and energy densities of this dark matter model. By numerically solving the system of coupled differential equations while considering full...
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Diego Nicolás Ordóñez Peña (Universidad Nacional de Colombia)06/11/2026, 15:50
La producción cosmológica gravitacional es conocida como el efecto de creación de partículas de un campo cuántico sobre un universo en expansión debida únicamente a la interacción gravitacional. Durante la fase de expansión acelerada del universo, un campo cuántico presenta excitaciones agresivas que modifican la forma en como crea y destruye partículas. Dado que el campo evoluciona desde un...
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Yeinzon Rodríguez García06/11/2026, 16:20
The cosmological principle demands statistical homogeneity and isotropy at large enough scales. Although this principle is firmly based on observations, the cosmological principle perhaps requires more than what is actually necessary, the latter being just isotropic expansion with no vorticity. This rationale has led to the formulation of what is called extended...
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