Related papers: Viscous {\Lambda}CDM Universe Models
In this article, the bulk viscosity is introduced in a modified gravity model. The gravitational action has a general $f(R,T)$ form, where $R$ and $ T $ are the curvature scalar and the trace of energy momentum tensor respectively. An…
Modern cosmology suggests that the Universe contains two dark components -- dark matter and dark energy -- both unkown in laboratory physics and both lacking direct evidence. Alternatively, a unified dark sector, described by a single…
We use the dispersion measure (DM) and redshift measurements of 24 localized fast radio bursts (FRBs) to compare cosmological models and investigate the Hubble tension. Setting a flat prior on the DM contribution from the Milky Way's halo,…
In this article, we have investigated the role of bulk viscosity to study the accelerated expansion of the universe in the framework of modified $f(Q)$ gravity. The gravitational action in this modified gravity theory has the form $f(Q)$,…
We investigate the virialization of cosmic structures in the framework of flat FLRW cosmological models, in which the vacuum energy density evolves with time. In particular, our analysis focuses on the study of spherical matter…
We study the bulk flow of the local universe using Type Ia supernova data by considering a class of cosmological model which is spatially flat,(FRW) space-times and contains cold dark matter and $Q$ component (QCDM models) of the fluid as a…
We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble…
We propose a bulk viscous unified dark matter scenario based on a nonlinear extension of the full causal Israel-Stewart theory. This framework allows the viscous fluid to remain far from equilibrium, an essential feature for a physically…
In this talk, we discuss one of the dissipative processes which likely take place in the Early Universe. We assume that the matter filling the isotropic and homogeneous background is to be described by a relativistic viscous fluid…
We consider cosmic chronometer (CC) data for the Hubble parameter, quasar (QSO) luminosities data of X-rays and ultraviolet rays emission, and the latest measurements of the present value of the Hubble parameter from 2018 Planck mission…
The current standard model of cosmology, the LambdaCDM model, is based on the homogeneous FLRW solutions of the Einstein equations to which some perturbations are added to account for the CMB features and structure formation at large…
Decaying vacuum models are a class of models that incorporate the vacuum energy density as a time-evolving entity that has the potential to explain the entire evolutionary history of the universe in a single framework. A general solution to…
We analyze how predictions of cosmological models depend on a choice of described observational data, restrictions on flatness, and how this choice can alleviate the $H_0$ tension. These effects are demonstrated in the $w$CDM model in…
It is found that the evolutions of density perturbations on the super-Hubble scales are unstable in the model with dark-sector interaction $Q$ proportional to the energy density of cold dark matter (CDM) $\rho_m$ and constant equation of…
The standard cosmological model, now strongly constrained by direct observation at early epochs, is very successful in describing the structure of the evolved universe on large and intermediate scales. Unfortunately, serious contradictions…
In this paper, we study the thermodynamical and mathematical consistencies for a non-singular early-time viscous cosmological model known as soft-Big Bang, which was previously found in [N. Cruz, E. Gonz\'alez, and J. Jovel, Phys. Rev. D…
The concept of negative temperatures has occasionally been used in connection with quantum systems. A recent example of this sort is reported in the paper of S. Braun et al. [Science 339,52 (2013)], where an attractively interacting…
Cosmological models with different types of Dark Energy are becoming viable alternatives for standard models with the cosmological constant. Yet, such models are more difficult to analyze and to simulate. We present analytical…
We use the hybrid model of bulk viscosity and generalized chaplygin gas (GCG), named the viscous generalized chaplygin gas (VGCG) model, which is thought to be an alternate dark fluid of the universe. We explore the dynamics of the VGCG…
We analyze a model for Dark Energy - Dark Matter interaction, based on a decaying process of the former into the latter. The dynamical equations are constructed following a kinetic formulation, which separates the interacting fluctuations…