scholarly journals Thermodynamic Analysis of the Static Spherically Symmetric Field Equations in Rastall Theory

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Hooman Moradpour ◽  
Ines G. Salako
Keyword(s):  
Event Horizon ◽  
Thermodynamic Quantities ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Mass Content ◽  
Field Equations ◽  
First Law Of Thermodynamics ◽  
Horizon Entropy ◽  
The One

The restrictions on the Rastall theory due to application of the Newtonian limit to the theory are derived. In addition, we use the zero-zero component of the Rastall field equations as well as the unified first law of thermodynamics to find the Misner-Sharp mass content confined to the event horizon of the spherically symmetric static spacetimes in the Rastall framework. The obtained relation is calculated for the Schwarzschild and de-Sitter back holes as two examples. Bearing the obtained relation for the Misner-Sharp mass in mind together with recasting the one-one component of the Rastall field equations into the form of the first law of thermodynamics, we obtain expressions for the horizon entropy and the work term. Finally, we also compare the thermodynamic quantities of system, including energy, entropy, and work, with their counterparts in the Einstein framework to have a better view about the role of the Rastall hypothesis on the thermodynamics of system.

scholarly journals Thermodynamic Analysis of Gravitational Field Equations in Lyra Manifold

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
H. Moradpour ◽  
N. Sadeghnezhad ◽  
S. Ghaffari ◽  
A. Jahan
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
De Sitter ◽  
Field Equations ◽  
Frw Universe ◽  
First Law Of Thermodynamics ◽  
Lyra Manifold ◽  
Symmetric Spacetimes ◽  
Horizon Entropy ◽  
Clausius Relation

Considering the Einstein field equations in Lyra manifold and applying the unified first law of thermodynamics as well as the Clausius relation to the apparent horizon of FRW universe, we find the entropy of apparent horizon in Lyra manifold. In addition, the validity of second law of thermodynamics and its generalized form are also studied. Finally, we use the first law of thermodynamics in order to find the horizon entropy of static spherically symmetric spacetimes. Some results of considering (anti)de-Sitter and Schwarzschild metrics have also been addressed.

scholarly journals Generalized Misner–Sharp energy in generalized Rastall theory

2020 ◽  
Vol 98 (9) ◽  
pp. 853-856
Author(s):  
H. Moradpour ◽  
M. Valipour
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Spherically Symmetric ◽  
Coupling Coefficients ◽  
Field Equations ◽  
Frw Universe ◽  
Einstein Theory ◽  
First Law Of Thermodynamics ◽  
Horizon Entropy ◽  
Friedmann Robertson Walker

Employing the unified first law of thermodynamics and the field equations of the generalized Rastall theory, we get the generalized Misner–Sharp mass of space–times for which gtt = –grr = –f(r). The obtained result differs from those of the Einstein and Rastall theories. Moreover, using the first law of thermodynamics, the obtained generalized Misner–Sharp mass, and the field equations, the entropy of static spherically symmetric horizons are also addressed in the framework of the generalized Rastall theory. In addition, by generalizing the study to a flat Friedmann–Robertson–Walker (FRW) universe, the apparent horizon entropy is also calculated. Considering the effects of applying the Newtonian limit to the field equations on the coupling coefficients of the generalized Rastall theory, our study indicates (i) the obtained entropy–area relation is the same as that of the Rastall theory, and (ii) the Bekenstein entropy is recovered when the generalized Rastall theory reduces to the Einstein theory. The validity of the second law of thermodynamics is also investigated in the flat FRW universe.

scholarly journals LUKEWARM BLACK HOLES IN QUADRATIC GRAVITY

2011 ◽  
Vol 26 (14) ◽  
pp. 999-1007 ◽  
Author(s):  
JERZY MATYJASEK ◽  
KATARZYNA ZWIERZCHOWSKA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Fourth Order ◽  
Spherically Symmetric ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Quadratic Gravity ◽  
De Sitter Universe ◽  
Electrically Charged

Perturbative solutions to the fourth-order gravity describing spherically-symmetric, static and electrically charged black hole in an asymptotically de Sitter universe is constructed and discussed. Special emphasis is put on the lukewarm configurations, in which the temperature of the event horizon equals the temperature of the cosmological horizon.

scholarly journals Thermodynamic properties of black holes in de Sitter space

2016 ◽  
Vol 32 (02) ◽  
pp. 1750017 ◽  
Author(s):  
Huai-Fan Li ◽  
Meng-Sen Ma ◽  
Ya-Qin Ma
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Thermodynamic Properties ◽  
Thermodynamic Quantities ◽  
De Sitter ◽  
First Law Of Thermodynamics ◽  
Effective Temperatures ◽  
Sds Black Hole

We study the thermodynamic properties of Schwarzschild–de Sitter (SdS) black hole and Reissner–Nordström–de Sitter (RNdS) black hole in view of global and effective thermodynamic quantities. Making use of the effective first law of thermodynamics, we can derive the effective thermodynamic quantities of de Sitter black holes. It is found that these effective thermodynamic quantities also satisfy Smarr-like formula. Especially, the effective temperatures are nonzero in the Nariai limit. By calculating heat capacity and Gibbs free energy, we find SdS black hole is always thermodynamically stable and RNdS black hole may undergoes phase transition at some points.

scholarly journals GRAVITATIONAL COLLAPSE OF SPHERICALLY SYMMETRIC PERFECT FLUID WITH KINEMATIC SELF-SIMILARITY

2002 ◽  
Vol 11 (02) ◽  
pp. 155-186 ◽  
Author(s):  
C. F. C. BRANDT ◽  
L.-M. LIN ◽  
J. F. VILLAS DA ROCHA ◽  
A. Z. WANG
Keyword(s):  
Black Holes ◽  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Self Similarity ◽  
Schwarzschild Solution ◽  
Naked Singularities

Analytic spherically symmetric solutions of the Einstein field equations coupled with a perfect fluid and with self-similarities of the zeroth, first and second kinds, found recently by Benoit and Coley [Class. Quantum Grav.15, 2397 (1998)], are studied, and found that some of them represent gravitational collapse. When the solutions have self-similarity of the first (homothetic) kind, some of the solutions may represent critical collapse but in the sense that now the "critical" solution separates the collapse that forms black holes from the collapse that forms naked singularities. The formation of such black holes always starts with a mass gap, although the "critical" solution has homothetic self-similarity. The solutions with self-similarity of the zeroth and second kinds seem irrelevant to critical collapse. Yet, it is also found that the de Sitter solution is a particular case of the solutions with self-similarity of the zeroth kind, and that the Schwarzschild solution is a particular case of the solutions with self-similarity of the second kind with the index α=3/2.

scholarly journals TORSION, DIRAC FIELD, DARK MATTER AND DARK RADIATION

2007 ◽  
Vol 22 (04) ◽  
pp. 835-850 ◽  
Author(s):  
PRASANTA MAHATO
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Lagrange Multipliers ◽  
Lagrangian Density ◽  
Dirac Field ◽  
De Sitter ◽  
Field Equations ◽  
Cartan Geometry ◽  
Dark Radiation

The role of torsion and a scalar field ϕ in gravitation, especially, in the presence of a Dirac field in the background of a particular class of the Riemann–Cartan geometry is considered here. Recently, a Lagrangian density with Lagrange multipliers has been proposed by the author which has been obtained by picking some particular terms from the SO (4, 1) Pontryagin density, where the scalar field ϕ causes the de Sitter connection to have the proper dimension of a gauge field. In this paper the scalar field has been linked to the dimension of the Dirac field. Here we get the field equations for the Dirac field and the scalar field in such a way that both of them appear to be mutually noninteracting. In this scenario the scalar field appears to be a natural candidate for the dark matter and the dark radiation.

DISCUSSION ON EVENT HORIZON AND QUANTUM ERGOSPHERE OF DYNAMIC DE SITTER BLACK HOLES

2012 ◽  
Vol 27 (04) ◽  
pp. 1250010
Author(s):  
BAI SHENG LIU ◽  
JING YI ZHANG
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Potential Barrier ◽  
Hawking Radiation ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Tunneling Process ◽  
Apparent Horizons ◽  
Symmetric Black Hole

In the paper, the tunneling framework is applied to calculate the local horizons of Vaidya–de Sitter black holes and Vaidya–Bonner–de Sitter black holes. The researches show that the quantum ergosphere of a spherically symmetric black hole is identical with the potential barrier set by the tunneling process. The calculations also indicate that both the apparent horizons of the dynamic de Sitter black hole produce Hawking radiation. The conclusions can be applicable to either the charged or uncharged particles' Hawking radiation.

scholarly journals Exact solutions of three-dimensional black holes: Einstein gravity versus F(R) gravity

2014 ◽  
Vol 23 (11) ◽  
pp. 1450088 ◽  
Author(s):  
S. H. Hendi ◽  
B. Eslam Panah ◽  
R. Saffari
Keyword(s):  
Black Hole ◽  
Exact Solutions ◽  
Three Dimensional ◽  
Einstein Gravity ◽  
Nonlinear Electrodynamics ◽  
Thermodynamic Quantities ◽  
Field Equations ◽  
First Law Of Thermodynamics ◽  
Conformally Invariant ◽  
Dimensional Spacetime

In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account (2 + 1)-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure F(R) gravity as well as F(R)-conformally invariant Maxwell (CIM) theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models.

scholarly journals String Theory Explanation of Galactic Rotation Found Using the Geodesic Constraint

2019 ◽  
Vol 2019 ◽  
pp. 1-4
Author(s):  
Mark D. Roberts
Keyword(s):  
String Theory ◽  
Low Energy ◽  
Galactic Rotation ◽  
Spherically Symmetric ◽  
Scalar Tensor Theory ◽  
De Sitter ◽  
Energy Limit ◽  
Field Equations ◽  
Tensor Theory ◽  
Spherically Symmetric Metric

The unique spherically symmetric metric which has vanishing Weyl tensor, is asymptotically de-Sitter, and can model constant galactic rotation curves is presented. Two types of field equations are shown to have this metric as an exact solution. The first is Palatini varied scalar-tensor theory. The second is the low energy limit of string theory modified by inclusion of a contrived potential.

scholarly journals Quantum-Gravity Stochastic Effects on the de Sitter Event Horizon

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 696 ◽  
Author(s):  
Claudio Cremaschini ◽  
Massimo Tessarotto
Keyword(s):  
Quantum Gravity ◽  
Event Horizon ◽  
Analytical Calculation ◽  
Tunneling Effect ◽  
Covariant Theory ◽  
De Sitter ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Metric Tensor ◽  
Stochastic Effects

The stochastic character of the cosmological constant arising from the non-linear quantum-vacuum Bohm interaction in the framework of the manifestly-covariant theory of quantum gravity (CQG theory) is pointed out. This feature is shown to be consistent with the axiomatic formulation of quantum gravity based on the hydrodynamic representation of the same CQG theory developed recently. The conclusion follows by investigating the indeterminacy properties of the probability density function and its representation associated with the quantum gravity state, which corresponds to a hydrodynamic continuity equation that satisfies the unitarity principle. As a result, the corresponding form of stochastic quantum-modified Einstein field equations is obtained and shown to admit a stochastic cosmological de Sitter solution for the space-time metric tensor. The analytical calculation of the stochastic averages of relevant physical observables is obtained. These include in particular the radius of the de Sitter sphere fixing the location of the event horizon and the expression of the Hawking temperature associated with the related particle tunneling effect. Theoretical implications for cosmology and field theories are pointed out.

Sign in / Sign up

Export Citation Format

Share Document