scholarly journals Benchmarking black hole heat engines, II

2018 ◽  
Vol 27 (16) ◽  
pp. 1950006 ◽  
Author(s):  
Avik Chakraborty ◽  
Clifford V. Johnson
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Velocity ◽  
Upper Bound ◽  
Exact Formula ◽  
Ideal Gas ◽  
Static Case ◽  
Rotating Black Hole ◽  
Heat Engines ◽  
Ads Black Holes

We extend to nonstatic black holes our benchmarking scheme that allows for cross–comparison of the efficiencies of asymptotically AdS black holes used as working substances in heat engines. We use a circular cycle in the [Formula: see text] plane as the benchmark cycle. We study Kerr black holes in four spacetime dimensions as an example. As in the static case, we find an exact formula for the benchmark efficiency in an ideal gas-like limit, which may serve as an upper bound for rotating black hole heat engines in a thermodynamic ensemble with fixed angular velocity. We use the benchmarking scheme to compare Kerr to static black holes charged under Maxwell and Born–Infeld sectors.

scholarly journals Holographic heat engines and static black holes: A general efficiency formula

2019 ◽  
Vol 28 (02) ◽  
pp. 1950030 ◽  
Author(s):  
Felipe Rosso
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Upper Bound ◽  
Heat Engine ◽  
Thermodynamic System ◽  
Ideal Gas ◽  
Heat Flows ◽  
Heat Engines ◽  
Static Black Hole

Starting from simple observations regarding heat flows for static black holes (or any thermodynamic system with [Formula: see text]), we get inequalities which restrict their change in energy and adiabatic curves in the [Formula: see text] plane. From these observations, we then derive an exact efficiency formula for virtually any holographic heat engine defined by a cycle in the [Formula: see text] plane, whose working substance is a static black hole. Moreover, we get an upper bound for its efficiency and show that for a certain class of black holes, this bound is universal and achieved by an “ideal gas” hole. Finally, we compute exact efficiencies for some particular and new engines.

Benchmarking black hole heat engines, I

2018 ◽  
Vol 27 (16) ◽  
pp. 1950012 ◽  
Author(s):  
Avik Chakraborty ◽  
Clifford V. Johnson
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Exact Result ◽  
Ideal Gas ◽  
Heat Engines ◽  
Gas System

We present the results of initiating a benchmarking scheme that allows for cross-comparison of the efficiencies of black holes used as working substances in heat engines. We use a circular cycle in the [Formula: see text] plane as the benchmark engine. We test it on Einstein–Maxwell, Gauss–Bonnet and Born–Infeld black holes. Also, we derive a new and surprising exact result for the efficiency of a special “ideal gas” system to which all the black holes asymptote.

scholarly journals Constraining the tidal charge of brane black holes using their shadows

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Juliano C. S. Neves
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Upper Bound ◽  
Brane World ◽  
Nonlocal Effect ◽  
Rotating Black Hole

Abstract A constraint on the tidal charge generated within a brane world is shown. Using the shadow of a rotating black hole in a brane context in order to describe the M87* parameters recently announced by the Event Horizon Telescope Collaboration, the deviation from circularity of the reported shadow produces an upper bound on the bulk’s nonlocal effect, which is conceived of as a tidal charge in the four-dimensional brane induced by the five-dimensional bulk. Therefore, a deviation from circularity $$\lesssim 10\%$$≲10% leads to an upper bound on the tidal charge $$\lesssim 0.004M^2$$≲0.004M2.

scholarly journals Central charges for AdS black holes

2021 ◽  
Author(s):  
Malcolm Perry ◽  
Maria J Rodriguez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Central Charge ◽  
Negative Cosmological Constant ◽  
Ads Black Holes ◽  
Kerr Black Holes ◽  
Distinguishing Features ◽  
Area Law ◽  
Cardy Formula

Abstract Nontrivial diffeomorphisms act on the horizon of a generic 4D black holes and create distinguishing features referred to as soft hair. Amongst these are a left-right pair of Virasoro algebras with associated charges that reproduce the Bekenstein-Hawking entropy for Kerr black holes. In this paper we show that if one adds a negative cosmological constant, there is a similar set of infinitesimal diffeomorphisms that act non-trivially on the horizon. The algebra of these diffeomorphisms gives rise to a central charge. Adding a boundary counterterm, justified to achieve integrability, leads to well-defined central charges with cL = cR. The macroscopic area law for Kerr-AdS black holes follows from the assumption of a Cardy formula governing the black hole microstates.

scholarly journals Deforming charged black holes with dipolar differential rotation boundary

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Tong-Tong Hu ◽  
Shuo Sun ◽  
Hong-Bo Li ◽  
Yong-Qiang Wang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Chemical Potential ◽  
Dimensional Space ◽  
Quasinormal Modes ◽  
Fixed Temperature ◽  
First Case ◽  
Ads Black Holes ◽  
Horizon Geometry ◽  
Black Hole Solutions

Abstract Motivated by the recent studies of the novel asymptotically global $$\hbox {AdS}_4$$AdS4 black hole with deformed horizon, we consider the action of Einstein–Maxwell gravity in AdS spacetime and construct the charged deforming AdS black holes with differential boundary. In contrast to deforming black hole without charge, there exists at least one value of horizon for an arbitrary temperature. The extremum of temperature is determined by charge q and divides the range of temperature into several parts. Moreover, we use an isometric embedding in the three-dimensional space to investigate the horizon geometry. The entropy and quasinormal modes of deforming charged AdS black hole are also studied in this paper. Due to the existence of charge q, the phase diagram of entropy is more complicated. We consider two cases of solutions: (1) fixing the chemical potential $$\mu $$μ; (2) changing the value of $$\mu $$μ according to the values of horizon radius and charge. In the first case, it is interesting to find there exist two families of black hole solutions with different horizon radii for a fixed temperature, but these two black holes have same horizon geometry and entropy. The second case ensures that deforming charged AdS black hole solutions can reduce to standard RN–AdS black holes.

scholarly journals Joule–Thomson expansion in AdS black hole with a global monopole

2018 ◽  
Vol 33 (35) ◽  
pp. 1850210 ◽  
Author(s):  
C. L. Ahmed Rizwan ◽  
A. Naveena Kumara ◽  
Deepak Vaid ◽  
K. M. Ajith
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Phase Space ◽  
Van Der Waals ◽  
Extended Phase Space ◽  
Global Monopole ◽  
Van Der Waals Gas ◽  
Extended Phase ◽  
Ads Black Holes

In this paper, we investigate the Joule–Thomson effects of AdS black holes with a global monopole. We study the effect of the global monopole parameter [Formula: see text] on the inversion temperature and isenthalpic curves. The obtained result is compared with Joule–Thomson expansion of van der Waals fluid, and the similarities were noted. Phase transition occuring in the extended phase space of this black hole is analogous to that in van der Waals gas. Our study shows that global monopole parameter [Formula: see text] plays a very important role in Joule–Thomson expansion.

Thermodynamic of the charged AdS black holes in Rastall gravity: P − V critical and Joule–Thomson expansion

2020 ◽  
Vol 35 (14) ◽  
pp. 2050113
Author(s):  
Sen Guo ◽  
Yan Han ◽  
Guo Ping Li
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Critical Temperature ◽  
Critical Exponents ◽  
State Equation ◽  
The State ◽  
Thermodynamic Quantities ◽  
Critical Temperatures ◽  
Ads Black Holes ◽  
And Inversion

In this paper, we study the thermodynamic of the charged AdS black holes in Rastall gravity. Firstly, the thermodynamic quantities of the charged AdS black holes in Rastall gravity are reviewed and the state equation of this black hole is obtained. Then, we investigate the [Formula: see text] critical and the Joule–Thomson expansion of the charged AdS black holes in Rastall gravity in which the critical temperature and the critical exponents are obtained. In addition, we get the inversion temperature and plot the isenthalpic and inversion curves in the [Formula: see text] plane, and also determine the cooling-heating regions of this black hole through the Joule–Thomson expansion. Finally, we investigate the ratio between the minimum inversion and critical temperatures, and find that the Rastall constant [Formula: see text] does not affect of this ratio.

scholarly journals Causality of black holes in 4-dimensional Einstein–Gauss–Bonnet–Maxwell theory

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Xian-Hui Ge ◽  
Sang-Jin Sin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Shear Viscosity ◽  
Upper Bound ◽  
Causal Structure ◽  
Density Ratio ◽  
Entropy Density ◽  
Coupling Constant ◽  
Maxwell Theory ◽  
Black Hole Solutions

Abstract We study charged black hole solutions in 4-dimensional (4D) Einstein–Gauss–Bonnet–Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. We then demonstrate how bulk causal structure analysis imposes an upper bound on the Gauss–Bonnet coupling constant in the AdS space. Causality constrains the value of Gauss–Bonnet coupling constant $$\alpha _{GB}$$αGB to be bounded by $$\alpha _{GB}\le 0$$αGB≤0 as $$D\rightarrow 4$$D→4.

scholarly journals The Thermodynamic Relationship between the RN-AdS Black Holes and the RN Black Hole in Canonical Ensemble

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yu-Bo Ma ◽  
Li-Chun Zhang ◽  
Jian Liu ◽  
Ren Zhao ◽  
Shuo Cao
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Flat Space ◽  
Space Time ◽  
Asymptotically Flat ◽  
Time Space ◽  
Ads Black Holes ◽  
Different Types ◽  
Thermodynamic Relationship ◽  
The Relationship

In this paper, by analyzing the thermodynamic properties of charged AdS black hole and asymptotically flat space-time charged black hole in the vicinity of the critical point, we establish the correspondence between the thermodynamic parameters of asymptotically flat space-time and nonasymptotically flat space-time, based on the equality of black hole horizon area in the two different types of space-time. The relationship between the cavity radius (which is introduced in the study of asymptotically flat space-time charged black holes) and the cosmological constant (which is introduced in the study of nonasymptotically flat space-time) is determined. The establishment of the correspondence between the thermodynamics parameters in two different types of space-time is beneficial to the mutual promotion of different time-space black hole research, which is helpful to understand the thermodynamics and quantum properties of black hole in space-time.

scholarly journals Extracting Hawking radiation near the horizon of AdS black holes

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Krishan Saraswat ◽  
Niayesh Afshordi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Evaporation Rate ◽  
Order Term ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Leading Order ◽  
Proper Distance ◽  
Ads Black Holes ◽  
A Cell

Abstract We study how the evaporation rate of spherically symmetric black holes is affected through the extraction of radiation close to the horizon. We adopt a model of extraction that involves a perfectly absorptive screen placed close to the horizon and show that the evaporation rate can be changed depending on how close to the horizon the screen is placed. We apply our results to show that the scrambling time defined by the Hayden-Preskill decoding criterion, which is derived in Pennington’s work (arXiv:1905.08255) through entanglement wedge reconstruction is modified. The modifications appear as logarithmic corrections to Pennington’s time scale which depend on where the absorptive screen is placed. By fixing the proper distance between the horizon and screen we show that for small AdS black holes the leading order term in the scrambling time is consistent with Pennington’s scrambling time. However, for large AdS black holes the leading order Log contains the Bekenstein-Hawking entropy of a cell of characteristic length equal to the AdS radius rather than the entropy of the full horizon. Furthermore, using the correspondence between the radial null energy condition (NEC) and the holographic c-theorem, we argue that the screen cannot be arbitrarily close to the horizon. This leads to a holographic argument that black hole mining using a screen cannot significantly alter the lifetime of a black hole.

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