Related papers: Viscous fluid dynamics with decaying vacuum energy…
We investigate the impact of bulk viscosity on the accelerating expansion and large-scale structure formation of a Universe in which the underlying gravitational interaction is described by $f(Q)$ gravity. Various paradigmatic choices of…
The standard formulation of General Relativity Theory, in the absence of a cosmological constant, is unable to explain the responsible mechanism for the observed late-time cosmic acceleration. On the other hand, by inserting the…
We study a cosmological model composed of a dark energy fluid interacting with a viscous matter fluid in a spatially flat Universe. The matter component represents the baryon and dark matter and it is taken into account, through a bulk…
In this paper we are to study homogeneous and anisotropic Bianchi type-V universe in presence of bulk viscous fluid source of matter with time function gravitational constant G and cosmological term lambda. The viscosity coefficient is…
Extending the standard $\Lambda$CDM model by considering dissipative effects within a causal viscous framework, and obtaining an analytical solution for the Hubble parameter remains a challenge in the literature. In this work, we resolve…
The present study deals with spatially homogeneous and totally anisotropic Bianchi type V cosmological model in presence of bulk viscous fluid source with time dependent gravitational constant G and cosmological term Lambda. The coefficient…
Bulk viscosity in cold dark matter is an appealing feature that introduces distinctive phenomenological effects in the cosmological setting as compared to the $\Lambda$CDM model. Under this view, we propose a general parametrization of the…
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…
In this paper, we study Friedmann cosmology with time-varying vacuum energy density in the context of Brans-Dicke theory. We consider an isotropic and homogeneous flat space, filled with a matter-dominated perfect fluid and a dynamical…
In this paper we consider dissipative effects in $\Lambda$CDM model, i.e., we consider a universe with cosmological constant having viscous matter. We assume the most general form for bulk viscous coefficient,…
We perform a global analysis of curved Friedmann-Robertson-Walker cosmologies in the presence of a viscous fluid. The fluid's bulk viscosity is governed by a first order theory recently proposed in [M. M. Disconzi, T. W. Kephart, and R. J.…
Among the several proposals to solve the incompatibility between the observed small value of the cosmological constant and the huge value obtained by quantum field theories, we can find the idea of a decaying vacuum energy density, leading…
In this research work, we investigate the late-time accelerated expansion of the universe within the framework of Brans-Dicke theory by considering dynamical vacuum energy models with a time-varying cosmological constant. Two vacuum energy…
All evolutional paths for all admissible initial conditions of FRW cosmological models with dissipative dust fluid (described by dark matter, baryonic matter and dark energy) are analyzed using dynamical system approach. With that approach,…
We investigate the properties of the FLRW flat cosmological models in which the vacuum energy density evolves with time, $\Lambda(t)$. Using different versions of the $\Lambda(t)$ model, namely quantum field vacuum, power series vacuum and…
In this paper, we investigate the existence of bulk viscous FLRW cosmological models in a recently proposed extended symmetric teleparallel gravity or $f\left( Q,T\right) $ gravity in which $Q$ is the non-metricity and $T$ is the trace of…
In the present paper, the effects of viscous dark matter are analysed within the $\Lambda$CDM model. Here we consider bulk viscosity through the Israel-Stewart theory approach, leading to an effective pressure term in the continuity…
Some Bianchi type IX viscous fluid cosmological models are investigated. To get a solution a supplementary condition between metric potentials is used. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of…
Bianchi type V viscous fluid cosmological model for barotropic fluid distribution with varying cosmological term $\Lambda$ is investigated. We have examined a cosmological scenario proposing a variation law for Hubble parameter $H$ in the…
We propose a new model for the viscosity of cosmic matters, which can be applied to different epochs of the universe. Using this model, we include the bulk viscosities as practical corrections to the perfect fluid models of the baryonic and…