Related papers: Interpretation of bulk viscosity as the generalize…
We consider the possibility of getting accelerated expansion and w=-1 crossing in the context of a braneworld cosmological setup, endowed with a bulk energy-momentum tensor. For a given ansatz of the bulk content, we demonstrate that the…
A flat FLRW cosmological model with perfect fluid comprising of variable Chaplygin gas has been studied in context of f(R; T) gravity with particle creation. The considered scale factors describe the accelerated expansion of universe due to…
The principles of General Relativity allow for a non-vanishing cosmological constant, which can possibly be interpreted at least partially in terms of quantum-fluctuations of matter fields. Depending on sign and magnitude it can cause…
We model the cosmological substratum by a viscous fluid that is supposed to provide a unified description of the dark sector and pressureless baryonic matter. In the homogeneous and isotropic background the \textit{total} energy density of…
We exploit the gauge-invariant formalism to analyse the perturbative behaviour of two cosmological models based on the generalized Chaplygin gas describing both dark matter and dark energy in the present Universe. In the first model we…
A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by cosmic structure formation, without resort to Dark Energy, modifications to gravity, or a local void. The observed acceleration…
In this essay, I present an alternative explanation for the cosmic acceleration which appears as a consequence of recent high redshift Supernova data. In the usual interpretation, this cosmic acceleration is explained by the presence of a…
Different models of the cosmic substratum which pretend to describe the present stage of accelerated expansion of the Universe like the $\Lambda$CDM model or a Chaplygin gas, can be seen as special realizations of a holographic dark energy…
In this article, we investigate the observed cosmic acceleration in the framework of a cosmological $f(R,L_m)$ model dominated by bulk viscous matter in an anisotropic background. We consider the LRS Bianchi type I metric and derive the…
A cosmology is considered driven by a stress-energy tensor consisting of a perfect fluid, an inhomogeneous pressure term (which we call a ``tachyonic dust'' for reasons which will become apparent) and a cosmological constant. The…
Motivated by recent developments in particle physics and cosmology, there has been growing interest in an unified description of dark matter and dark energy scenarios. In this paper we explore observational constraints from age estimates of…
Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the…
We present a discussion of the effects induced by the bulk viscosity on the very early Universe stability. The matter filling the cosmological (isotropic and homogeneous) background is described by a viscous fluid having an…
The purpose of the present work is two folded: (1) we propose a new mechanism for the origin of bulk viscosity in cosmological context, and then, (2) we address the thermodynamic implications of viscous cosmology based on the thermodynamics…
The discovery that the expansion of the Universe is accelerating is the most challenging problem of modern cosmology. In the context of general relativity, there are many dark energy candidates to explain the observed acceleration. In this…
The cosmological constant, which was introduced by Einstein a century ago to allow for a static universe, experienced a revival two decades ago under the label dark energy as a parameter to model the observed accelerated expansion of the…
In this work we explore an alternative phenomenological model to Chaplygin gas proposed by H. Hova et. al., consisting on a modification of a perfect fluid, to explain the dynamics of dark matter and dark energy at cosmological scales…
The analytic properties of the energy density rho(t) of the cosmic fluid, and the Hubble parameter H(t), are investigated near to the future singularity t=t_s assuming different forms for the equation of state. First, it is shown that the…
In this study, we explore the accelerated expansion of the universe within the framework of modified $f(Q)$ gravity. The investigation focus on the role of bulk viscosity in understanding the universe's accelerated expansion. Specifically,…
We present a general relativistic version of the self-gravitating fluid model for the dark sector of the Universe (darkon fluid) introduced in Phys. Rev. 80 (2009) 083513 and extended and reviewed in Entropy (2013) 559. This model contains…