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Yeinzon Rodriguez15/09/2022, 09:00
We study the consistency of the decoupling limit of the generalized SU(2) Proca theory (GSU2P). Namely, we study the healthiness of those terms whose analysis in the scalar limit was not originally established in the reconstruction of the full theory (see the work by Gallego Cadavid et al. [Phys. Rev. D 102, 104066 (2020)]). Those terms are the parity-violating $\tilde{\mathcal{L}}^1_{4,2}$...
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Ms Melissa Varela Álvarez (Universidad del Valle)15/09/2022, 09:45
In this work, we study a dark energy model solely based on gauge vector fields, coupled to dark matter. We use the dynamical system approach to investigate the stability of this proposal and identify both, scaling and late-time accelerating solutions. Then, we numerically integrate the equations that characterize the dynamics of the model to verify the results of the previous analysis and...
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JOSE LUIS PALACIOS CORDOBA (Universidad Del Valle)15/09/2022, 10:10
We investigate the cosmic effects of a Proca-type vector field coupled to cold dark matter (CDM). We compute the cosmological perturbations and the background evolution of the model by implementing it in the Boltzmann code CLASS. The interaction term was chosen as a $Qf(X)\rho_{cdm}$, where $Q$ is a coupling constant, $f(X)$ is a polynomial function of the vector field $A_{\mu}$, and...
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PEDRO MARTIN IBARBO PERLAZA (Universidad del Valle)15/09/2022, 11:00
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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SANTIAGO GARCIA SERNA15/09/2022, 11:25
We study a dark energy (DE) model based on a tachyon field $\phi$ coupled to a vector field in a Bianchi-I anisotropic background. We consider that the potential of the tachyon field $V$ and the coupling function $f$ satisfy the differentials equations $\alpha=M_{pl}V_{,\phi}/V^{3/2}$ and $\beta=\left(M_{pl}f_{,\phi}\right)/\left(f\sqrt{V}\right)$ respectively, where $M_{pl}$ is the reduced...
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Brayan Elian Castiblanco Ortigoza (Universidad Nacional de Colombia)15/09/2022, 11:50
The type-I Dirac seesaw extension is made to the DFSZ axion model, where light active neutrinos are Dirac particles and acquire mass through the
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canonical seesaw mechanism after the Peccei-Quinn and electroweak symmetry breaking, finding that neutrino mass is given by m_{\nu} ≈ 𝑣𝑓{𝑎}/Λ{𝑈𝑉},
result which relates the three energy scales involved in the model: the mass of the heavy sterile... -
Juan Felipe Bravo Cardenas (National University of Colombia)15/09/2022, 14:00
En los últimos años las simulaciones numéricas han jugado un papel muy importante como complemento a las pruebas a las cuales es sometida constantemente la Relatividad General. Un caso particular es la Relatividad Numérica, con la cual se dificultaría la comprensión de
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fenómenos astrofísicos como la colisión de agujeros negros. Desde la astrofísica también se puede estudiar como planetas y... -
william jaimes15/09/2022, 14:25
We study the frame-dragging effect in the context of slowly rotating stars in Horndeski theory (HT) and Generalized Proca theory (GPT). The frame-dragging effect occurs when a rotating compact object distorts spacetime and inertial observers are dragged along when they are infree fall from infinity. James Hartle developed a methodology to study this effect for slowly rotating stars in the...
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Mr Itamar Alfonso Lopez Trilleras (Universidad Nacional de Colombia)15/09/2022, 14:50
Two methods for mass profiles reconstruction in disc-like galaxies are presented in this work, the first is done with the fit of the rotation curve based on the data of circular velocity which are obtained observationally in a stars system, while the other method is focused in the Gravitational Lensed Effect (GLE). For these mass reconstructions, two routines developed in the language of...
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Cesar A. Valenzuela-Toledo (Departamento de Física, Universidad del Valle)15/09/2022, 15:40
In general, modified gravity theories can be seen as dark energy theories using the effective fluid approach. In this work, we apply this formalism to the most general second-order scalar-vector-tensor (SVT) theory of gravity. This will allow us to encompass all the free functions of the theory in terms of the equation of state, speed of sound, velocity, and anisotropic stress of a very...
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Daniel Molano (Universidad de los Andes)15/09/2022, 16:05
Argumentos teóricos y observacionales sugieren que la Relatividad General (RG) quizás no sea el modelo gravitacional definitivo. Por ende, se han propuesto una serie de extensiones a la RG, en las cuales es complejo encontrar soluciones exactas a las ecuaciones propuestas. Las técnicas perturbativas desarrolladas en RG son importantes para poder encontrar descripciones físicas y matemáticas de...
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Cesar Daniel Peralta Gonzalez (Universidad Antonio Nariño)15/09/2022, 16:30
In this work we analyze the stability criteria in f(R) theories of gravity in the metric formalism under the approach of a thermodynamics analogy proposed in [C.D. Peralta and S.E. Jorás JCAP06(2020)053] for ϕ^4 and double well inflationary potentials. We starting from the mentioned potentials in the Einstein frame, and obtain a parametric form of f(R) in the corresponding Jordan frame. Such...
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Jaime Forero-Romero (Universidad de los Andes)16/09/2022, 09:00
El Dark Energy Spectroscopic Instrument (DESI) es a la fecha es el único experimento activo de medición de energía oscura de Etapa IV utilizando oscilaciones acústicas bariónicas y otras técnicas que se basan en mediciones espectroscópicas. Se espera que el proyecto tome datos hasta el año 2026.
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A través de la Universidad de los Andes, Colombia es uno de los países que cuentan con... -
Daniel Felipe Forero Sanchez (EPFL)16/09/2022, 09:45
Our understanding of the Universe in its largest scales relies on our ability to accurately simulate the complexities of gravitational evolution, thus allowing us to test various cosmological models. Moreover, the increasing volume of the observations of our Universe and the nature of the targeted galaxies impose strong conditions on the size and mass resolution of these N-body simulations,...
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Jaime Forero-Romero (Universidad de los Andes)16/09/2022, 10:10
In this work, we study the correlation between galaxy orientations and filaments of the cosmic web using observational measurements. We used bright galaxies observations from the Dark Energy Spectroscopic Instrument (DESI). The cosmic web filaments were computed using the Discrete Persistent Source Extractor (DisPerSE) algorithm. We found the closest filament segment to each galaxy. These...
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Luz Ángela García (Universidad ECCI)16/09/2022, 11:00
We introduce an effective parametrization of an early dark energy model that mimics radiation at early times and governs the present acceleration of the Universe. We show that such a parametrization can be modeled by a Chaplygin gas and investigate the cosmological viability of the model. We use a Bayesian method and the modular software \textsc{CosmoSIS} to find the best values for the free...
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ANDRES DAVID FLOREZ QUINTERO (Universidad del Valle)16/09/2022, 11:25
En este trabajo se analiza la dinámica cosmológica de un sólido; es decir, una tríada de campos escalares no-homogéneos que en conjunto preservan la isotropía y homogeneidad del universo de fondo. Utilizando la técnica de sistemas dinámicos, encontramos que este sistema no posee atractores acelerados. Este análisis se complementa con soluciones numéricas. Estas soluciones particulares muestran...
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Carlos Eduardo Cedeño Montaña (Centro Brasilerio de Pesquisas Físicas)16/09/2022, 11:50
The spacetime of a boosted Bondi-Sachs rotating black hole is considered as a proper background to examine electromagnetic configurations connected to analytic solutions of Maxwell equations. In our analysis, we first use the Bondi-Sachs transformations in order to bring the boosted rotating black hole metric into the Kerr-Schild form, from which zero angular momentum observers (ZAMOs) are...
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victor loaiza16/09/2022, 14:00
The large scale structures on the universe are best described by the cold dark matter model which only fails on sub-galaxy scales known as the small scale crisis. There has been a recently proposed model of dark matter, where cold dark matter is modeled by a complex scalar field, which follows a Schrödinger equation with a non-linear potential which satisfies a Poisson equation. This...
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Jeison Stiven Lenis Trujillo (Universidad del Valle)16/09/2022, 14:25
The formation of structures in the universe is studied with the help of a dynamical cold dark matter model addressed as the Schrödinger-Poisson model. The Schrödinger-Poisson equation (SPE) is obtained from the Vlasov-Poisson equation which is derived in a perturbation regime of the fluid equations in the Newtonian regime. The SPE is restricted to one dimension and numerically integrated using...
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ALEJANDRO ESTRADA LLESTA16/09/2022, 14:50
In this talk, we will present an analytical and numerical approach for constructing initial data sets of inhomogeneous cosmological spacetimes with a spatial topology of $\mathbb{T}^3$. On the one hand, the analytical part is based on a 2+1 decomposition of the so-called constraint equations, which are a set of tensorial equations that determine the initial data in general relativity, to turn...
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Joel Jose Velasquez Celis (Universidad Nacional de Colombia)16/09/2022, 15:40
Debido a las observaciones del CMB y de las supernovas tipo I se puede concluir que el universo se está expandiendo de manera acelerada. La aceleración del universo se puede explicar mediante el modelo ΛCDM, el cual considera que el universo estaría compuesto en su mayoría por la constante cosmológica Λ, una forma de Energía Oscura, y de Materia Oscura Fría. Sin embargo, este modelo no explica...
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Tatiana Ortega-Quintero (Universidad de Antioquia), Camilo Delgado-Correal (Francisco José de Caldas District University of Bogotá)16/09/2022, 16:05
The standard analysis of the rotation curves of spiral galaxies suggested the presence of a dark matter component in those galaxies, however there are other models that suggest other explanations to explain the Non-Keplerian behavior.
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In this work we studied the rotation curves of spiral galaxies by using different models of diverse physical nature that give us an understanding of them... -
Juan Sierra (None)16/09/2022, 16:30
In order to get a better understanding of the Large Scale Structure, physics must find a way to account for the observable universe components, given the fact that in order to build a theory of the LSS, it needs to include many of the known phenomena such as hydrodynamics, electrodynamics, spacetime curvature, the behavior of baryonic matter, quantum particle dynamics as well as models for the...
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Leonardo Castañeda Colorado (Universidad Nacional de Colombia)16/09/2022, 16:55
Problemas físicos tales como conducción de calor, la ley de Hooke, la conservación de la
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carga eléctrica, para mencionar unos pocos, están escritos matemáticamente en términos de
ecuaciones diferenciales parciales (EDPs). Por lo tanto, es importante y además imperativo
entender y desarrollar métodos que lleven a solucionar este tipo de ecuaciones. Además, es
vital considerar que las... -
Sergio Manuel Cubides Pérez (Universidad Industrial de Santander)
We apply the $\delta N$ formalism to study the spectrum and bispectrum of the primordial curvature perturbation $\zeta$ for the constant-roll inflation scenario where $\zeta$ is generated by vector field perturbations of a cosmic triad background field configuration. This is studied in the Friedmann-Lemaître-Robertson-Walker space-time background and in the framework of the generalized $SU(2)$...
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