Thermodynamical and observational aspects of cosmological model with linear equation of state

2018 ◽  
Vol 15 (08) ◽  
pp. 1850129 ◽  
Author(s):  
G. P. Singh ◽  
Nikhil Hulke ◽  
Ashutosh Singh
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Cosmological Model ◽  
Linear Equation ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Generalized Second Law ◽  
Slow Roll ◽  
General Conditions

In this paper, a cosmological model with linear equation of state in the framework of General relativity is studied. We explore the thermodynamical aspects of the cosmological model with equilibrium description. In particular, we discuss the validity of generalized second law of thermodynamics for resulting cosmologies. General conditions for this model to satisfy the slow roll conditions for inflation are discussed.

Aspects of nonflat FRW bouncing models with quadratic equation of state

2018 ◽  
Vol 33 (35) ◽  
pp. 1850213 ◽  
Author(s):  
Ashutosh Singh ◽  
Rakesh Raushan ◽  
R. Chaubey ◽  
T. Singh
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Bulk Viscosity ◽  
Second Law Of Thermodynamics ◽  
Quadratic Equation ◽  
Energy Conditions ◽  
Second Law ◽  
Generalized Second Law ◽  
Quadratic Equation Of State

In this paper, we investigate the possibility of a nonsingular model of universe in the framework of general relativity in nonflat FRW geometries with quadratic equation of state and bulk viscosity. We study whether a nonsingular bounce requires violation of energy conditions. We discuss the thermodynamical aspects of the resulting models with equilibrium description. In particular, we discuss the validity of the generalized second law of thermodynamics for resulting cosmologies.

Cosmological consequences of modified Friedmann equations according to holographic equipartition law

2021 ◽  
Vol 36 (10) ◽  
pp. 2150069
Author(s):  
Abdul Jawad ◽  
Sidra Saleem ◽  
Saba Qummer
Keyword(s):  
Equation Of State ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Om Diagnostic ◽  
Generalized Second Law ◽  
Friedmann Equations ◽  
Equation Of State Parameter ◽  
Equipartition Law

We examine thermodynamically an extra driving term for the flat universe by applying Sharma Mittal entropy to Padmanabhan’s holographic equipartition law. Deviations from the Bekenstein–Hawking entropy by using this law, we generate an extra driving in the acceleration equation. By using the constant and parametrized equation of state parameter, we investigate the different cosmological parameters like deceleration parameter, squared speed of sound, Om-diagnostic and statefinder parameter through graphical approach. We observe compatible results with current observational data in both models. Generalized second law of thermodynamics also remains valid in both cases.

Bianchi type-II universe with linear equation of state

Open Physics ◽  
2014 ◽  
Vol 12 (8) ◽  
Author(s):  
Kishor Adhav ◽  
Ishwar Pawade ◽  
Abhijit Bansod
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Cosmological Model ◽  
Linear Equation ◽  
Bianchi Type ◽  
Type Ii ◽  
Field Equations ◽  
Expansion Scalar ◽  
Shear Scalar

AbstractWe have studied anisotropic and homogeneous Bianchi type-II cosmological model with linear equation of state (EoS) p = αρ−β, where α and β are constants, in General Relativity. In order to obtain the solutions of the field equations we have assumed the geometrical restriction that expansion scalar θ is proportional to shear scalar σ. The geometrical and physical aspects of the model are also studied.

scholarly journals Qualitative aspects of Rastall gravity with barotropic fluid

2021 ◽  
Author(s):  
Ashutosh Singh ◽  
Rakesh Raushan ◽  
R. Chaubey
Keyword(s):  
Dynamical System ◽  
Equation Of State ◽  
System Approach ◽  
Apparent Horizon ◽  
Dynamical Evolution ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Frw Universe ◽  
Barotropic Fluid ◽  
Generalized Second Law

We investigate the dynamical evolution of homogeneous and isotropic flat-FRW universe filled with a barotropic fluid satisfying linear equation of state in Rastall gravity. Using dynamical system approach, we find the fixed points of the system and study their stability. We further explore the thermodynamic aspects at the apparent horizon by investigating the validity of generalized second law of thermodynamics with equilibrium description.

The barrow holographic dark energy-based reconstruction of f(R) gravity and cosmology with Nojiri–Odintsov cutoff

2021 ◽  
pp. 2150148
Author(s):  
Amrita Sarkar ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Holographic Dark Energy ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Transition Model ◽  
Late Time ◽  
Reconstruction Scheme ◽  
Generalized Second Law ◽  
Special Case

In the work reported here we have considered Barrow holographic dark energy (BHDE) proposed in E. N. Saridakis, Barrow holographic dark energy, Phys. Rev. D 102 (2020) 123525 as a special case of more generalized version of Nojiri–Odintsov holographic dark energy (NOHDE) proposed in S. I. Nojiri and S. D. Odintsov, Unifying phantom inflation with late-time acceleration: Scalar phantom–non-phantom transition model and generalized holographic dark energy, Gen. Relativ. Gravit. 38 (2006) 1285–1304 and also reconstructed [Formula: see text] gravity with BHDE as the form of background evolution. It has been observed that in the case of BHDE reconstructed [Formula: see text] gravity the equation of state can have a transition from quintessence to phantom. In a particular case of reconstruction, possibility of Little Rip singularity has been observed. Finally, the generalized second law of thermodynamics has been found to be valid under this reconstruction scheme.

Thermodynamics in loop quantum cosmology with non-canonical scalar field model

2019 ◽  
Vol 16 (06) ◽  
pp. 1950081
Author(s):  
Ayesha Iqbal ◽  
Abdul Jawad
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
Equilibrium Condition ◽  
Field Model ◽  
State Parameter ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Generalized Second Law ◽  
Equation Of State Parameter ◽  
The Universe

The cosmological scenario is built up within the framework of scalar field model possessing a noncanonical kinetic term in loop quantum gravity. The noncanonical scalar field is permitted to interact with dark matter field by assuming a specific form of coupling term. The equation of state parameter is set to be constant as well as variable (Chevallier–Polarski–Linder parametrization) and evaluated the behavior of universe through deceleration parameter and weak energy condition. These parameters favor the accelerated expansion of the universe for three values of equation of state parameter in both cases allowed by observational data. The squared speed of sound leads to the stability of the underlying models in both forms of equation of state parameter. Moreover, the validity of generalized second law of thermodynamics is analyzed by using first law of thermodynamics and assume the universe to be enclosed by apparent horizon. The Bekenstein, logarithmic and power-law entropy is being considered as entropy of horizon. The thermodynamic equilibrium condition is also discussed for all three cases of entropies. The generalized second law of thermodynamics and thermal equilibrium condition is satisfied for all the three types of entropies.

scholarly journals The generalized second law in chameleon cosmology

2011 ◽  
Vol 89 (9) ◽  
pp. 915-919 ◽  
Author(s):  
H. Farajollahi ◽  
A. Salehi ◽  
F. Tayebi
Keyword(s):  
Equation Of State ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Total Entropy ◽  
Generalized Second Law ◽  
Phantom Crossing ◽  
Hubble Parameters ◽  
The Universe

In this paper, we investigate the validity of the generalized second law of thermodynamics in flat Friedmann–Lemaître–Robertson–Walker chameleon cosmology where the boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. It has been shown that, in a bouncing scenario for the universe with phantom crossing, the total entropy decreases with time in the contracting epoch, whereas, the dynamics of the internal and horizon entropies depend on the behaviour of both the equation of state and the Hubble parameters.

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