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 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.

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 Black hole thermodynamics and heat engines in conformal gravity

2017 ◽  
Vol 26 (13) ◽  
pp. 1750151 ◽  
Author(s):  
Hao Xu ◽  
Yuan Sun ◽  
Liu Zhao
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Conformal Gravity ◽  
Extended Phase ◽  
Heat Engines ◽  
Equation Of States ◽  
Symmetric Black Hole ◽  
Black Hole Solutions

The extended phase-space thermodynamics and heat engines for static spherically symmetric black hole solutions of four-dimensional conformal gravity are studied in detail. It is argued that the equation of states (EOS) for such black holes is always branched, any continuous thermodynamical process cannot drive the system from one branch of the EOS into another branch. Meanwhile, the thermodynamical volume is bounded from above, making the black holes always super-entropic in one branch and may also be super-entropic in another branch in certain range of the temperature. The Carnot and Stirling heat engines associated to such black holes are shown to be distinct from each other. For rectangular heat engines, the efficiency always approaches zero when the rectangle becomes extremely narrow, and given the highest and lowest working temperatures fixed, there is always a maximum for the efficiency of such engines.

scholarly journals THERMODYNAMIC GEOMETRY AND CRITICAL BEHAVIOR OF BLACK HOLES

2007 ◽  
Vol 22 (01) ◽  
pp. 11-27 ◽  
Author(s):  
JIANYONG SHEN ◽  
RONG-GEN CAI ◽  
BIN WANG ◽  
RU-KENG SU
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Critical Behavior ◽  
Hessian Matrix ◽  
Black Hole Entropy ◽  
De Sitter ◽  
Ads Black Holes ◽  
Gas System ◽  
The One

Based on the observations that there exists an analogy between the Reissner–Nordström–Anti-de Sitter (RN–AdS) black holes and the van der Waals–Maxwell liquid-gas system, in which a correspondence of variables is (ϕ,q) ↔ (V,P), we study the Ruppeiner geometry, defined as Hessian matrix of black hole entropy with respect to the internal energy (not the mass) of black hole and electric potential (angular velocity), for the RN, Kerr and RN–AdS black holes. It is found that the geometry is curved and the scalar curvature goes to negative infinity at the Davies' phase transition point for the RN and Kerr black holes. Our result for the RN–AdS black holes is also in good agreement with the one about phase transition and its critical behavior in the literature.

scholarly journals Effects of the external string cloud on the Van der Waals-like behavior and efficiency of AdS-Schwarzschild black holes in massive gravity

2020 ◽  
Vol 35 (24) ◽  
pp. 2050203
Author(s):  
M. Ghanaatian ◽  
Mehdi Sadeghi ◽  
Hadi Ranjbari ◽  
Gh. Forozani
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Van Der Waals ◽  
Black Hole Entropy ◽  
Five Dimensions ◽  
Four Dimensions ◽  
Heat Engines ◽  
Cloud Parameter ◽  
Extremal Black Holes

In this paper, we study AdS-Schwarzschild black holes in four and five dimensions in dRGT minimally coupled to a cloud of strings. It is observed that the entropy of the string cloud and massive terms does not affect the black hole entropy. The observations about four dimensions indicate that the massive term in the presence of external string cloud cannot exhibit Van der Waals-like behavior for AdS-Schwarzschild black holes and, therefore there is only the Hawking–Page phase transition. In contrast, in five dimensions, the graviton mass modifies this behavior through the third massive term, so that a critical behavior and second-order phase transition is deduced. Also, the Joule–Thomson effect is not observed. The black hole stability conditions are also studied in four and five dimensions and a critical value for the string cloud parameter is presented. In five dimensions a degeneracy between states for extremal black holes is investigated. After studying black holes as thermodynamic systems, we consider such systems as heat engines, and finally the efficiency of them is calculated.

scholarly journals Thermodynamics of the Bardeen black hole in anti-de Sitter space

2019 ◽  
Vol 34 (40) ◽  
pp. 1950336
Author(s):  
Cong Li ◽  
Chao Fang ◽  
Miao He ◽  
Jiacheng Ding ◽  
Jianbo Deng
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
De Sitter Space ◽  
Capacity Analysis ◽  
De Sitter ◽  
Gas System ◽  
Minimal Radius

In this paper, we study thermodynamics of the regular black holes with Bardeen–AdS black hole. The cut-off radius which is the minimal radius of the stable Bardeen–AdS black hole has been obtained from temperature and heat capacity analysis, respectively. Moreover, the thermodynamical stability of the Bardeen–AdS black hole is learned by the Gibbs free energy and the heat capacity. In this work, we find similar properties to the van der Waals liquid-gas system.

scholarly journals Thermodynamics and heat engines of black holes with Born–Infeld-type electrodynamics

2021 ◽  
pp. 2150102
Author(s):  
Leonardo Balart ◽  
Sharmanthie Fernando
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Phase Transitions ◽  
Heat Engine ◽  
Nonlinear Electrodynamics ◽  
Extended Phase ◽  
Charged Black Holes ◽  
Heat Engines ◽  
Two Parameters ◽  
Electrically Charged

In this paper, we have studied electrically charged black holes in a new model of nonlinear electrodynamics introduced by Kruglov in Mod. Phys. Lett. A 32, 1750201 (2017). There are two parameters for the theory and the black hole could have up to two horizons. Thermodynamics is studied in the extended phase space where the pressure is proportional to the cosmological constant. First law and the Smarr formula are derived. There are phase transitions similar to the Van der Waals liquid-gas phase transitions. Black hole is also studied as a heat engine and we have discussed how the parameters in the nonlinear electrodynamics theory affect the efficiency of the heat engine.

scholarly journals Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

2021 ◽  
Vol 503 (3) ◽  
pp. 3629-3642
Author(s):  
Colin DeGraf ◽  
Debora Sijacki ◽  
Tiziana Di Matteo ◽  
Kelly Holley-Bockelmann ◽  
Greg Snyder ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Star Formation ◽  
Morphological Evolution ◽  
Full Range ◽  
High Mass ◽  
Morphological Evidence ◽  
Galaxy Mergers ◽  
Host Galaxies ◽  
Supermassive Black Hole

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

scholarly journals Islands and stretched horizon

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yoshinori Matsuo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Total System ◽  
Island Rule ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Ads Spacetime ◽  
Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

scholarly journals Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 279
Author(s):  
Zdeněk Stuchlík ◽  
Jaroslav Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Observational Data ◽  
High Frequency ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Periodic Oscillations ◽  
High Length ◽  
Circular Geodesic

We study epicyclic oscillatory motion along circular geodesics of the Simpson–Visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. We give the frequencies of the orbital and epicyclic motion in a Keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. We use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (HF QPOs) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of HF QPOs observational data from the surrounding of supermassive black holes. We demonstrate that this is really possible for wormholes with sufficiently high length parameter l.

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