We present compact object solutions in the Generalized SU(2) Proca theory (GSU2P), including boson stars, neutron stars, and black holes. This modified gravity model is a vector-tensor theory, invariant under global SU(2) transformations, and incorporates second-order derivative self-interactions of the vector field, extending beyond the massive Yang-Mills theory. Initially, we investigated...
This project has as its general objective the extension of the classical formulation of gravity, considering it not only as a geometric theory but as a consequence of the laws of thermodynamics applied to accelerated observers. The general case involving curvature, torsion, and non-metricity was addressed and allowed us to generalize the famous T. Jacobson's result in which he identifies the...
En este trabajo teórico, investigamos diferentes modelos para predecir el redshift (z) de las ráfagas rápidas de radio (FRB; Fast Radio Bursts en inglés) de su medida de dispersión (DM; dispersion measure) observada y otras propiedades reportadas. Realizamos una revisión exhaustiva de la literatura de los FRBs con galaxia hospedera confirmada y construimos el catálogo más actualizado a la...
With recent results coming from the last releases of DES, pointing to a reduction in the significance of the Hubble tension, the focus is now shifting to study the shape of the dark energy (DE) equation of state (EOS). The Hubble tension is the discrepancy between the values of (H_0) determined from the magnitude-redshift relation and those derived from the Cosmic Microwave Background (CMB)....
A dark matter medium composed of ultra-light axion-like particles (ALPs) with electromagnetic couplings can induce a birefringence effect in the polarization of photons emitted by pulsars. We have developed a robust and comprehensive method to search for such birefringence effects using polarimettry measurements from the Parkes Pulsar Timing Array (PPTA) and the QUIJOTE experiment targeting...
Se explora un modelo de energía oscura dinámica de multicampos que incluye dos campos escalares $\phi^a$ y $\phi^b$, los cuales están mínimamente acoplados a la gravedad. En este modelo, las trayectorias en el espacio de campos no son geodésicas, sino trayectorias giratorias. Los campos tienen componentes radiales y angulares, pero debido a la imposición de una simetría de desplazamiento en...
Very Special Linear Gravity (VSL-Gravity) is an alternative model of linearized gravity that incorporates massive gravitons while retaining two physical degrees of freedom due to gauge invariance. Recently, the model's gravitational period decay dynamics have been calculated using effective field theory techniques. In this study, we conduct a comprehensive Bayesian analysis of the PSR B1913+16...
In this talk, we will introduce the Cosmology Group at Universidad del Valle (UniValle), a hub for innovative research in theoretical cosmology. We will provide an overview of our current projects, which span topics such as modified gravity, dark energy, and the large-scale structure of the cosmos.
We are also actively involved in the development and application of advanced computational...
In the context of the Bianchi universes, i.e., homogeneous but anisotropic cosmologies, we study the conditions to obtain vanishing shear which indeed satisfies the cosmological principle. The anisotropic curvature has to be balanced by the anisotropic stresses of the non-perfect fluid that dominates the energy density of the universe. Such a fluid has been considered to describe a n-form...
A quintessence cosmological model with an exponential potential $V(\phi) = V_0 e^{-\lambda \phi}$ is explored to explain the accelerated expansion of the universe. This model introduces a scalar field $\phi$, whose dynamics are governed by the parameter $\lambda$, which is linked to the evolution rate of dark energy. One of the key aspects of this study is the inclusion of spatial curvature,...
En el ámbito de la Relatividad General y las teorías extendidas de la gravedad, obtener soluciones para escenarios de interés físico representa un desafío altamente complejo. Mediante el uso del formalismo de la teoría de perturbaciones matemáticas en el marco de la Relatividad General, demostramos que, para una clase significativa de teorías de vacío $f(R, R_{\mu\nu}R^{\mu\nu})$, las...
One of the most striking features of the large-scale universe is the observed web-like pattern in the distribution of galaxies, forming clusters, filaments, and voids. This cosmic structure, known as the Cosmic Web, plays a crucial role in galaxy formation and evolution. To investigate this relationship, we employ the NEXUS_tidal algorithm to analyse the matter distribution from IllustrisTNG...
In the era of precision cosmology, large-scale structure analyses are essential for understanding the fundamental components that describe the distribution of galaxies. The J-PAS (Javalambre Physics of the Accelerating Universe Astrophysical Survey) is a promising galaxy survey designed to precisely measure photometric redshifts for galaxies up to z~1. Its redshift accuracy will not only allow...
En las últimas cinco décadas, la teoría de perturbaciones cosmológicas ha tenido un progreso significativo, producto de los avances tecnológicos en las observaciones y el esfuerzo de diversos grupos de investigación que han optimizado sus modelos teóricos y computacionales para describir, de forma aproximada, cómo ha evolucionado el campo de densidad, dando lugar a las estructuras...
