Related papers: Exploring the low redshift universe: two parametri…
The COBE microwave background temperature fluctuations and the abundance of local rich clusters of galaxies provide the two most powerful constraints on cosmological models. When all variants of the standard cold dark matter (CDM) model are…
All observational evidence for dark matter and dark energy is so far exclusively gravitational. Hence, the dark sector may be equivalently described by a theory of the spacetime metric whose dynamics is affected by interactions with an…
One of the possible extensions of Einstein's General Theory of Relativity consists in allowing for the presence of spacetime torsion. The form of the underlying torsion tensor can be chosen such that the homogeneity and isotropy of…
We derive a redshift drift formula for the spherically symmetric inhomogeneous pressure Stephani universes which are complementary to the spherically symmetric inhomogeneous density Lema\^itre-Tolman-Bondi models. We show that there is a…
We present the idea that replacing the cosmological constant $\Lambda$ in the $\Lambda$CDM model by a distribution of walls, with very low tension compared to what one would expect from new physics, could help explaining the tension in the…
We have considered a spatially flat, homogeneous and isotropic FLRW Universe filled with a single fluid, known as logotropic dark fluid (LDF), whose pressure evolves through a logarithmic equation of state. We use the recent Pantheon SNIa…
One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to uncover the nature of cosmic acceleration. In the base analysis, possible deviations from the Lambda-Cold-Dark-Matter ($\Lambda$CDM) background evolution will…
We consider spherically symmetric inhomogeneous dust models with a positive cosmological constant, $\Lambda$, given by the Lemaitre-Tolman-Bondi metric. These configurations provide a simple but useful generalization of the Lambda-CDM model…
We propose a fully nonlinear framework to construct consistency relations for testing generic cosmological scenarios using the evolution of large scale structure. It is based on the covariant approach in combination with a frame that is…
We study the reconstructed deceleration parameter splitting the data in different redshift bins, fitting both a cosmographic luminosity distance and also assuming a flat $\Lambda$CDM model, using the Pantheon+ sample of type Ia supernova…
The standard model of cosmology is based on two unknown dark components that are uncoupled from each other. In this paper we investigate whether there is evidence for an interaction between these components of cold dark matter (CDM) and…
Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein's cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy…
We explore the effects of a positive cosmological constant on astrophysical and cosmological configurations described by a polytropic equation of state. We derive the conditions for equilibrium and stability of such configurations and…
The current cosmological model, known as the $\Lambda$-Cold Dark Matter model (or $\Lambda$CDM for short) is one of the most astonishing accomplishments of contemporary theoretical physics. It is a well-defined mathematical model which…
In the current era of precision cosmology, the persistence of cosmological tensions, most notably the Hubble tension and the $S_8$ tension, challenges the standard $\Lambda$CDM model. To reconcile these tensions via late-time modifications…
The considerable difference between early and late universe measurements of the Hubble constant, called the Hubble tension, poses a potential challenge to the standard $\Lambda$CDM cosmological model. We examine an interacting dark…
We present updated observational constraints on the spatially flat $\phi$CDM model, where dark energy is described by a minimally coupled scalar field $\phi$ with an inverse power-law potential $V=V_0 \phi^{-\alpha}$. Using Planck 2018 CMB…
We consider a varieties of quintessence scalar field models in a homogeneous and isotropic geometry of the universe with zero spatial curvature aiming to provide stringent constraints using a series of cosmological data sets, namely, the…
We discuss how dynamical dark energy universes with exotic singularities may be distinguished from the standard $\Lambda$CDM model on the basis of their redshift drift signal, for which measurements both in the acceleration phase and in the…
We investigate Dark Energy by associating it with vacuum energy or Cosmological constant ${\Lambda}$ which is taken to be dynamic in nature. Our approach is phenomenological and falls within the domain of variable-$\Lambda$ Cosmology.…