A logarithmic equation of state

Cosmological models with inhomogeneous viscous fluids with a logarithmic equation of state in the Friedmann-Lemaitre-Robertson-Walker universe are considered. The influence of thermal effects caused by Hawking radiation on the visible horizon of the Universe on the change in the type of singularity of the dark Universe is investigated. It is shown that under the influence of thermal radiation, taking into account the viscosity property of a dark fluid, a qualitative change in the type of the Big Rip singularity is possible, which can lead to the absence of a singularity in the Universe at all.

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The limiting behavior of the Riemann solution to the isentropic Euler system for logarithmic equation of state with a source term

Mathematical Methods in the Applied Sciences ◽

10.1002/mma.7254 ◽

2021 ◽

Author(s):

Anupam Sen ◽

T. Raja Sekhar

Keyword(s):

Equation Of State ◽

Source Term ◽

Euler System ◽

Limiting Behavior ◽

Riemann Solution ◽

Logarithmic Equation

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The intrinsic phenomena of cavitation and concentration in Riemann solutions for the isentropic two-phase model with the logarithmic equation of state

Journal of Mathematical Physics ◽

10.1063/5.0058618 ◽

2021 ◽

Vol 62 (10) ◽

pp. 101502

Author(s):

Meina Sun

Keyword(s):

Equation Of State ◽

Phase Model ◽

Two Phase ◽

Riemann Solutions ◽

Logarithmic Equation

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Viscous accelerating universe with nonlinear and logarithmic equation of state fluid

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887819501500 ◽

2019 ◽

Vol 16 (10) ◽

pp. 1950150

Author(s):

I. Brevik ◽

A. N. Makarenko ◽

A. V. Timoshkin

Keyword(s):

Equation Of State ◽

Accelerated Expansion ◽

Accelerating Universe ◽

Late Time ◽

Viscosity Effects ◽

Logarithmic Equation ◽

The Universe ◽

Gravitational Equations ◽

Universe Evolution ◽

Friedmann Robertson Walker

We describe the accelerated expansion of the late-time universe using a generalized equation of state (EoS) when account is taken of bulk viscosity. We assume a homogeneous and isotropic Friedmann–Robertson–Walker spacetime. Solutions of the gravitational equations for dark energy are obtained in implicit form. Characteristic properties of the universe evolution in the presence of the viscosity effects are discussed. Finally, the dynamics of the accelerated expansion of the viscous universe are discussed on the basis of a modified logarithmic-corrected EoS.

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