Magnetic nonsingular black holes in lovelock gravity coupled to exponential electrodynamics

2021 ◽  
pp. 2150162
Author(s):  
Askar Ali
Keyword(s):  
Black Holes ◽  
Magnetic Charge ◽  
Thermodynamic Quantities ◽  
Lovelock Gravity ◽  
Critical Dimensions ◽  
Spacetime Geometry ◽  
New Class ◽  
Asymptotic Expressions ◽  
Dimensional Spacetime ◽  
Metric Function

The model of exponential electromagnetic field is coupled to Lovelock gravitational field in [Formula: see text]-dimensional spacetime geometry. In this context, new class of magnetically charged nonsingular or regular Lovelock black holes has been introduced. The asymptotic behavior of resulting metric function in the vicinity of [Formula: see text] is studied. The obtained asymptotic expressions in both even and odd critical dimensions show the finiteness and regularity of the solution at [Formula: see text]. The thermodynamic quantities such as Hawking temperature and specific heat capacity at constant magnetic charge corresponding to the nonsingular black hole are computed. The tunneling probability associated with Hawking radiations from these black holes is calculated as well.

scholarly journals Thermal fluctuations and correlations among hairs of a stable quantum black hole: Some examples

2018 ◽  
Vol 33 (33) ◽  
pp. 1850190 ◽  
Author(s):  
Aloke Kumar Sinha
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Electric Charge ◽  
Magnetic Charge ◽  
Thermal Fluctuations ◽  
Horizon Area ◽  
Dimensional Spacetime ◽  
Newman Black Hole ◽  
Area Limit

We have already derived the criteria for thermal stability of charged rotating quantum black holes, for horizon areas that are large relative to the Planck area. The derivation is done by using results of loop quantum gravity and equilibrium statistical mechanics of the grand canonical ensemble. We have also showed that in four-dimensional spacetime, quantum AdS Kerr–Newman black hole and asymptotically AdS dyonic black hole with electric and magnetic charge are thermally stable within certain range of its parameters. In this paper, the expectation values of fluctuations and correlations among horizon area, electric charge and angular momentum (magnetic charge) of these black holes are calculated within their range of stability. Interestingly, it is found that leading order fluctuations of electric charge and angular momentum (magnetic charge), in large horizon area limit, are independent of the values of electric charge and angular momentum (magnetic charge) at equilibrium.

scholarly journals EXTREMAL MYERS–PERRY BLACK HOLES COUPLED TO BORN–INFELD ELECTRODYNAMICS IN ODD DIMENSIONS

2014 ◽  
Vol 23 (04) ◽  
pp. 1450032 ◽  
Author(s):  
MASOUD ALLAVERDIZADEH ◽  
SEYED H. HENDI ◽  
JOSÉ P. S. LEMOS ◽  
AHMAD SHEYKHI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Third Order ◽  
Seed Solution ◽  
New Class ◽  
Angular Momenta ◽  
Dimensional Spacetime ◽  
Extremality Condition ◽  
Black Hole Solutions ◽  
Odd Dimensions

Employing higher-order perturbation theory, we find a new class of perturbative extremal rotating black hole solutions with Born–Infeld electric charge in odd D dimensional spacetime. The seed solution is an odd-dimensional extremal Myers–Perry black hole with equal angular momenta to which a perturbative, nonlinear, electric Born–Infeld field charge q is added maintaining the extremality condition. The perturbations are performed up to third-order. We also study some physical properties of these black holes. In particular, it is shown that the values of the gyromagnetic ratio of the black holes are modified by the perturbative parameter q and the Born–Infeld parameter β.

scholarly journals GRAVITY-WAVE DETECTORS AS PROBES OF EXTRA DIMENSIONS

2005 ◽  
Vol 14 (12) ◽  
pp. 2347-2353 ◽  
Author(s):  
CHRIS CLARKSON ◽  
ROY MAARTENS
Keyword(s):  
Black Holes ◽  
String Theory ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Extra Dimensions ◽  
State Of The Art ◽  
Three Dimensional ◽  
Observable Universe ◽  
Dimensional Spacetime ◽  
Higher Dimensional

If string theory is correct, then our observable universe may be a three-dimensional "brane" embedded in a higher-dimensional spacetime. This theoretical scenario should be tested via the state-of-the-art in gravitational experiments — the current and upcoming gravity-wave detectors. Indeed, the existence of extra dimensions leads to oscillations that leave a spectroscopic signature in the gravity-wave signal from black holes. The detectors that have been designed to confirm Einstein's prediction of gravity waves, can in principle also provide tests and constraints on string theory.

scholarly journals Thermal stability of black holes with arbitrary hairs

2018 ◽  
Vol 33 (05) ◽  
pp. 1850031 ◽  
Author(s):  
Aloke Kumar Sinha
Keyword(s):  
Thermal Stability ◽  
Black Holes ◽  
Loop Quantum Gravity ◽  
Canonical Ensemble ◽  
Grand Canonical Ensemble ◽  
Stability Criteria ◽  
Spacetime Geometry ◽  
Rotating Black Holes ◽  
Grand Canonical ◽  
Thermal Stability Of

We have derived the criteria for thermal stability of charged rotating black holes, for horizon areas that are large relative to the Planck area (in these dimensions). In this paper, we generalized it for black holes with arbitrary hairs. The derivation uses results of loop quantum gravity and equilibrium statistical mechanics of the grand canonical ensemble and there is no explicit use of classical spacetime geometry at all in this analysis. The assumption is that the mass of the black hole is a function of its horizon area and all the hairs. Our stability criteria are then tested in detail against some specific black holes, whose metrics provide us with explicit relations for the dependence of the mass on the area and other hairs of the black holes. This enables us to predict which of these black holes are expected to be thermally unstable under Hawking radiation.

General Relativity

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Field Equation ◽  
Einstein Field Equation ◽  
Kerr Metric ◽  
Gravitational Lenses ◽  
Field Equations ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Rotating Black Holes

This chapter presents the physical motivation for general relativity, derives the Einstein field equation and gives concise derivations of the main results of the theory. It begins with the equivalence principle, tidal forces in Newtonian gravity and their connection to curved spacetime geometry. This leads to a derivation of the field equation. Tests of general relativity are considered: Mercury’s perihelion advance, gravitational redshift, the deflection of starlight and gravitational lenses. The exterior and interior Schwarzschild solutions are discussed. Eddington–Finkelstein coordinates are used to describe objects falling into non-rotating black holes. The Kerr metric is used to describe rotating black holes and their astrophysical consequences. Gravitational waves are described and used to explain the orbital decay of binary neutron stars. Their recent detection by LIGO and the beginning of a new era of gravitational wave astronomy is discussed. Finally, the gravitational field equations are derived from the Einstein–Hilbert action.

Entropy bound of horizons of some regular black holes

2020 ◽  
Vol 35 (10) ◽  
pp. 2050070
Author(s):  
Ujjal Debnath
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Specific Heat ◽  
Surface Area ◽  
Event Horizon ◽  
Specific Heat Capacity ◽  
Thermodynamic Quantities ◽  
Event Horizons ◽  
Regular Black Hole

We study the four-dimensional (i) modified Bardeen black hole, (ii) modified Hayward black hole, (iii) charged regular black hole and (iv) magnetically charged regular black hole. For modified Bardeen black hole and modified Hayward black hole, we found only one horizon (event horizon) and then we found some thermodynamic quantities like the entropy, surface area, irreducible mass, temperature, Komar energy and specific heat capacity on the event horizon. We here study the bounds of the above thermodynamic quantities for these black holes on the event horizon. Then, we examine the thermodynamics stability of the black holes with some conditions. Next, we studied the charged regular black hole and magnetically charged regular black hole and found two horizons (Cauchy and event horizons) of these black holes. Then, we found the entropy, surface area, irreducible mass, temperature, Komar energy and specific heat capacity on the Cauchy and event horizons. Then, we get some conditions for thermodynamic stability/instability of the black holes. We found the radius of the extremal horizon and Christodoulou–Ruffiini mass and then analyze the above thermodynamic quantities on the extremal horizon. We calculate the sum/subtraction, product, division and sum/subtraction of inverse of surface areas, entropies, irreducible masses, temperatures, Komar energies and specific heat capacities on both the horizons. From these, we found the bounds of the above quantities on the horizons.

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 Ten shades of black

2015 ◽  
Vol 24 (12) ◽  
pp. 1544007 ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Radiation Spectrum ◽  
Black Hole Physics ◽  
Black Body ◽  
Black Hole Radiation ◽  
Dimensional Spacetime ◽  
Opposite Behavior ◽  
Curvature Potential ◽  
Energy Dependent

The holographic principle has taught us that, as far as their entropy content is concerned, black holes in (3 + 1)-dimensional curved spacetimes behave as ordinary thermodynamic systems in flat (2 + 1)-dimensional spacetimes. In this paper, we point out that the opposite behavior can also be observed in black-hole physics. To show this we study the quantum Hawking evaporation of near-extremal Reissner–Nordström (RN) black holes. We first point out that the black-hole radiation spectrum departs from the familiar radiation spectrum of genuine (3 + 1)-dimensional perfect black-body emitters. In particular, the would be black-body thermal spectrum is distorted by the curvature potential which surrounds the black-hole and effectively blocks the emission of low-energy quanta. Taking into account the energy-dependent gray-body factors which quantify the imprint of passage of the emitted radiation quanta through the black-hole curvature potential, we reveal that the (3 + 1)-dimensional black holes effectively behave as perfect black-body emitters in a flat (9 + 1)-dimensional spacetime.

Thermodynamic geometry of charged dilaton black holes in AdS spaces

2016 ◽  
Vol 94 (10) ◽  
pp. 1045-1053 ◽  
Author(s):  
Ahmad Sheykhi ◽  
Seyed Hossein Hendi ◽  
Fatemeh Naeimipour ◽  
Shahram Panahiyan ◽  
Behzad Eslam Panah
Keyword(s):  
Black Holes ◽  
Ricci Scalar ◽  
Thermodynamic Quantities ◽  
Geometrical Approach ◽  
De Sitter ◽  
Ads Black Holes ◽  
Divergence Points ◽  
The Stability ◽  
Thermodynamical Behavior ◽  
Dilaton Black Holes

It was shown that with the combination of three Liouville-type dilaton potentials, one can derive dilaton black holes in the background of anti-de-Sitter (AdS) spaces. In this paper, we further extend the study on the dilaton AdS black holes by investigating their thermodynamic instability through a geometry approach. First, we review thermodynamic quantities of the solutions and check the validity of the first law of thermodynamics. Then, we investigate phase transitions and stability of the solutions. In particular, we disclose the effects of the dilaton field on the stability of the black holes. We also employ the geometrical approach toward thermodynamical behavior of the system and find that the divergencies in the Ricci scalar coincide with roots and divergencies in the heat capacity. We find that the behavior of the Ricci scalar around divergence points depends on the type of the phase transition.

scholarly journals Thermodynamics of black holes in Rastall gravity

2018 ◽  
Vol 27 (07) ◽  
pp. 1850069 ◽  
Author(s):  
Iarley P. Lobo ◽  
H. Moradpour ◽  
J. P. Morais Graça ◽  
I. G. Salako
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
General Relativity ◽  
Black Hole ◽  
Momentum Conservation ◽  
Thermodynamic Quantities ◽  
Horizon Radius ◽  
Thermodynamics Of Black Holes ◽  
Matter Fields ◽  
Energy Momentum Conservation

A promising theory in modifying general relativity (GR) by violating the ordinary energy–momentum conservation law in curved spacetime is the Rastall theory of gravity. In this theory, geometry and matter fields are coupled to each other in a nonminimal way. Here, we study thermodynamic properties of some black hole (BH) solutions in this framework, and compare our results with those of GR. We demonstrate how the presence of these matter sources amplifies the effects caused by the Rastall parameter in thermodynamic quantities. Our investigation also shows that BHs with radius smaller than a certain amount ([Formula: see text]) have negative heat capacity in the Rastall framework. In fact, it is a lower bound for the possible values of horizon radius satisfied by the stable BHs.

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