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Dr LEON DARIO ESCOBAR DIAZ (Universidad del Valle)21/09/2023, 09:00
Within the framework of general relativity, the concept of local mass (or quasi-local mass) aims to quantify the amount of mass contained within a particular region of space-time. Nevertheless, the precise definition of such mass in accordance with the theory of general relativity continues to be an unresolved matter. Over the past few decades, numerous proposals have emerged in an attempt to...
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JOHN BAYRON ORJUELA-QUINTANA (UNIVERSIDAD DEL VALLE)21/09/2023, 09:45
The matter power spectrum $P(k)$ is one of the main quantities connecting observational and theoretical cosmology. Although for a fixed redshift this can be numerically computed very efficiently by Boltzmann solvers, an analytical description is always desirable. However, accurate fitting functions for $P(k)$ are only available for the concordance model. Taking into account that forthcoming...
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Yeimy Dallana Camargo Camargo (Universidad Nacional de Colombia)21/09/2023, 10:15
The Next Generation Illustris simulations (IllustrisTNG) have shown a remarkable match with the observed clustering properties of galaxies, providing us with a unique opportunity to study the relationship between the assembly times of galaxies, the color ($g-i$) and the specific Star Formation Rate (sSFR) with the assembly times of their host dark-matter (DM) haloes. To quantify this...
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Daniel Alexdy Torres Ballesteros (Universidad Nacional de Colombia), Prof. Leonardo Castañeda Colorado (Universidad Nacional de Colombia)21/09/2023, 11:05
En este trabajo presentamos relensing, un método que busca modelar cúmulos de galaxias haciendo uso del efecto de lente gravitacional. Hemos implementado un método no paramétrico (o de forma-libre) el cual determina el potencial deflector sobre una red irregular adaptativa. Para poder modelar un cúmulo de galaxias, relensing hace uso de sistemas de múltiples imágenes (régimen fuerte), al...
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Rigoberto Angel Casas Miranda (Universidad Nacional de Colombia)21/09/2023, 11:35
The Local Group, dominated by the main galaxies: the Milky Way and the Andromeda galaxy, presents a scenario where a set of satellite galaxies orbiting around one of these two galaxies is observed. These satellites do not present an isotropic distribution, but rather the majority are located on a plane almost perpendicular to the plane of the galaxy’s disk. In the case of the Milky Way, the...
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William Jaimes21/09/2023, 14:00
We study the frame-dragging effect in the context of slowly rotating stars in Horndeski theory (HT), Generalized Proca theory (GPT) and Generalized SU(2) Proca theory (GSU2P). The last two differ in that while GPT does not have internal simmetries, the GSU2P is invariant under SU(2) group of global transformations. The frame-dragging effect occurs when a rotating compact object distorts...
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Diego Mauricio Gallego Mahecha (Universidad Pedagógica y Tecnológica de Colombia.)21/09/2023, 14:30
We present partial results from a model constructed using conventional components found in string compactification as well as in general supersymmetric theories. The model entails a pair of scalar fields coupled through non-trivial kinetic mixing and incorporates a $U(1)$ vector field with a field dependent gauge kinetic function. The system unveils a novel fixed point within a Bianchi I...
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JOHN BAYRON ORJUELA-QUINTANA (UNIVERSIDAD DEL VALLE)21/09/2023, 15:00
Within the framework of modified gravity, the quasi-static and sub-horizon approximations are widely used in analyses aiming to identify departures from the concordance model at late-times. In general, it is assumed that time derivatives are subdominant with respect to spatial derivatives given that the relevant physical modes are those well inside the Hubble radius. In practice, the...
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Jose Fernando Rodriguez Ruiz (Universidad Industrial de Santander)21/09/2023, 15:50
In this work, we studied some compact object solutions in the Generalized SU(2) Proca theory. This modified gravity model is a vector-tensor theory whose action is invariant under global transformations of the SU(2) group and includes second-order derivative self-interactions of the vector field beyond the massive Yang-Mills theory. First, we studied two Lagrangian pieces consisting of four...
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Mr PEDRO MARTIN IBARBO PERLAZA (Universidad del Valle)21/09/2023, 16:20
Se presentará un estudio del proceso de formación de estructuras a gran escala en el Universo, en el marco del modelo del colapso esférico, para diferentes escenarios de energía oscura. Se consideran modelos de energía oscura con ecuaciones de estado dinámicas construidas a partir del análisis fenomenológico y otras construidas a partir de campos, con el objetivo de evaluar los efectos del...
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Luz Ángela García (Universidad ECCI)22/09/2023, 09:00
Accurate quasar classifications and redshift measurements are increasingly important to precision cosmology experiments. Broad absorption line (BAL) features are present in 15-20% of all quasars, and these features can introduce systematic redshift errors, and in extreme cases produce misclassifications. We quantitatively investigate the impact of BAL features on quasar classifications and...
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SANTIAGO GARCIA SERNA22/09/2023, 09:45
In the framework of the generalized Proca theories, we derive for the first time the most general Lagrangian allowing for scaling solutions between dark energy and cold dark matter. At background level, we highlight two interesting features for this novel model. Firstly, although its equation of state of is exactly $-1$, the dark energy component has a dynamical behaviour due to its coupling...
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Jhan Nicolás Martínez Lobo (Universidad Industrial de Santander)22/09/2023, 10:15
The generalized SU(2) Proca theory is a vector-tensor modified gravity theory where the action is invariant under both diffeomorphisms and global internal transformations of the SU(2) group. This work constitutes the first approach to investigate the physical properties of the theory at astrophysical scales. We have found solutions that naturally generalize the particle-like solutions of the...
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Ms GABRIELA ALEJANDRA VALENCIA ZUÑIGA (Universidad del Valle)22/09/2023, 11:05
It seems that if time travel is possible, it is inevitable to encounter paradoxes. These paradoxes include consistency paradoxes, such as the famous grandfather paradox, and bootstrap paradoxes, in which something is created out of nothing. The concept of parallel timelines is suggested to address these paradoxes, and a model called "Entangled Timelines" or E-CTCs is proposed to explain the...
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William Jaimes22/09/2023, 11:35
La teoría newtoniana de la gravedad puede ser reformulada en el lenguaje de geometría diferencial como una teoría no relativista en espaciotiempo curvo, en donde la fuente de la curvatura está asociada con el potencial gravitacional newtoniano estándar. Ésta es conocida como la teoría de Newton-Cartan (NC), y aunque a nivel dinámico es absolutamente equivalente a la teoría newtoniana estándar,...
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William Esteban Salazar (Centre for Bioinformatics and Photonics (CIBioFi), Universidad del Valle, Edificio E20 No. 1069, 760032 Cali, Colombia)22/09/2023, 14:00
In this talk, we investigate the spherical collapse model within the framework of dynamical dark energy cosmologies. We present a versatile code that allows for the implementation of various dark energy models, providing a powerful tool for studying their effects on structure formation. To demonstrate the capabilities of our code, we focus on a cosmology where a non-abelian gauge SU(2) vector...
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Diego Fernando Fonseca Moreno (Universidad Nacional de Colombia/ Universidad Antonio Nariño)22/09/2023, 14:30
In modern cosmology, the problem of large-scale structure formation has been studied through various analytical and computational methods and has become a cornerstone of astrophysics. The complexity of the equations that describe the evolution of small fluctuations in the matter field, with respect to the Friedmann - Lemaître - Robertson - Walker (FLRW) universe, commonly known as the theory...
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EDUARDO JOSE ORDOÑEZ HURTADO22/09/2023, 15:20
Con frecuencia, se ha recurrido a campos escalares como potenciales fuentes de inflación y energía oscura, dado que son capaces de generar presiones negativas requeridas para este tipo de fenómenos. Sin embargo, en esta ocasión, se ha explorado un enfoque diferente al considerar campos vectoriales no homogéneos como posibles fuentes de energía oscura.
En esta investigación, se ha empleado...
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Sebastian Rueda Blanco (Universidad Nacional de Colombia)
In this work we reviewed parametrizations of Dark Energy (DE) models focusing on potential late-time physics effects that could alleviate the Hubble Tension. We present a preliminary evaluation of the DE models proposed by Pan et. al. 2019, which consist of phenomenological parametrizations of the DE equation of state, $w = P/\rho$, in terms of the current value, $w_{0}$. In addition, we...
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Eduard Fernando Piratova Moreno (Fundación Universitaria Los Libertadores)
En este trabajo, presentamos un modelo de difusión en un marco cosmológico para describir la expansión acelerada del Universo en la época actual. Primero exploramos la introducción un campo escalar en las ecuaciones de campo de Einstein para explicar el efecto de la difusión como el generador de la expansión actual. Una vez que se forman las galaxias, el campo escalar entrega energía al fluido...
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