相关论文: Temperature Variation in the Dark Cosmic Fluid in …

A variety of conditions is considered under which the cosmic dark fluid may be able to develop a future Big Rip or Little Rip singularity. Both one-component and two-component models are considered. In the last-mentioned case we present a…

As first part of this work, experimental information about the decay of isotropic turbulence in ordinary hydrodynamics, u^2(t) proportional to t^{-6/5}, is used as input in FRW equations in order to investigate how an initial fraction f of…

In this work we explore the thermodynamic aspects of dark energy for late future time universe in two different scenarios: as a perfect fluid with constant and variable equation of state parameter; and as dissipative fluid described by a…

We study cosmological perturbations in a model of unified dark matter and dark energy with a sharp transition in the late-time universe. The dark sector is described by a dark fluid which evolves from an early stage at redshifts $z > z_C$…

Choosing various natural forms for the equation-of-state parameter w and the bulk viscosity \zeta, we discuss how it is possible for a dark energy fluid to slide from the quintessence region across the divide w=-1 into the phantom region,…

We investigate the turbulence effect in dark fluid universe with linear inhomogeneous equation of state. Attention is attached to two physical situations. First, we perform the perturbative analysis of turbulence and check its effects…

Specific dark energy models with a linear inhomogeneous time-dependent equation of state, within the framework of 4d Friedman-Robertson-Walker (FRW) cosmology, are investigated. It is demonstrated that such 4d inhomogeneous fluid models may…

In this paper, we attempt to explore the possibility of a obtaining a viable emergent universe scenario supported by a type of fluid known as the extended Chaplygin gas, which extends a modification to the equation of state of the well…

This work explores the influence of viscous fluids on cosmological dynamics within the framework of General Relativity. We introduce a novel time-dependent parametrization for the bulk viscosity coefficient, given by \(\zeta = \zeta_0 (t -…

Cosmological models with an inhomogeneous viscous dark fluid, coupled with dark matter in the Friedmann- Robertson-Walker (FRW) flat universe, are considered. The influence of thermal effects caused by Hawking radiation on the visible…

We study constraints from the latest CMB, large scale structure (2dF, Abell/ACO, PSCz) and SN1a data on dark energy models with a sharp transition in their equation of state, w(z). Such a transition is motivated by models like vacuum…

We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region…

We consider the late-time accelerated universe in the Friedmann-Robertson-Walker (FRW) spacetime with a nonzero curvature, and investigate cosmological models when the cosmic fluid is taken to be inhomogeneous and viscous (bulk viscous),…

We describe the evolution of the early and late universe from thermodynamic considerations, using the generalized non-extensive Tsallis entropy with a variable exponent. A new element in our analysis is the inclusion of a bulk viscosity in…

We analyze characteristic properties of two different cosmological models: (i) a one-component dark energy model where the bulk viscosity $\zeta$ is associated with the fluid as a whole, and (ii) a two-component model where $\zeta$ is…

The bulk viscosity of cosmological fluid and the creation of cold dark matter both result in the generation of irreversible entropy (related to dissipative processes) in a homogeneous and isotropic universe. To consider such effects, the…

Many have speculated about the presence of a stiff fluid in very early stage of the universe. Such a stiff fluid was first introduced by Zel'dovich. Recently the late acceleration of the universe was studied by taking bulk viscous stiff…

Using the previously developed model to describe laminar/turbulent states of a viscous fluid flow, which treats the flow as a collection of coherent structures of various size (Chekmarev, Chaos, 2013, 013144), the statistical temperature of…

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…

We discuss a cosmology in which cold dark matter begins to decay into relativistic particles at a recent epoch (z < 1). We show that the large entropy production and associated bulk viscosity from such decays leads to an accelerating…