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...
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...
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...
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
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...
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
fenómenos astrofísicos como la colisión de agujeros negros. Desde la astrofísica también se puede estudiar como planetas y...
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...
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...
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...
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...
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.
A través de la Universidad de los Andes, Colombia es uno de los países que cuentan con...
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,...
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...
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...
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...
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...
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...
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...
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.
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...
Problemas físicos tales como conducción de calor, la ley de Hooke, la conservación de la
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...
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 $SU(2)$...
