scholarly journals Extremal black holes that are not extremal: maximal warm holes

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Óscar J. C. Dias ◽  
Gary T. Horowitz ◽  
Jorge E. Santos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Temperature ◽  
Charged Scalar ◽  
Asymptotically Flat ◽  
Charged Black Holes ◽  
Maximum Charge ◽  
Scalar Hair ◽  
Hairy Black Hole ◽  
Extremal Black Holes

Abstract We study a family of four-dimensional, asymptotically flat, charged black holes that develop (charged) scalar hair as one increases their charge at fixed mass. Surprisingly, the maximum charge for given mass is a nonsingular hairy black hole with nonzero Hawking temperature. The implications for Hawking evaporation are discussed.

scholarly journals Inside an asymptotically flat hairy black hole

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Óscar J. C. Dias ◽  
Gary T. Horowitz ◽  
Jorge E. Santos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Holographic Superconductor ◽  
Charged Scalar ◽  
General Argument ◽  
Asymptotically Flat ◽  
Charged Black Holes ◽  
Scalar Hair ◽  
Hairy Black Hole

Abstract We study the interior of a recently constructed family of asymptotically flat, charged black holes that develop (charged) scalar hair as one increases their charge at fixed mass. Inside the horizon, these black holes resemble the interior of a holographic superconductor. There are analogs of the Josephson oscillations of the scalar field, and the final Kasner singularity depends very sensitively on the black hole parameters near the onset of the instability. In an appendix, we give a general argument that Cauchy horizons cannot exist in a large class of stationary black holes with scalar hair.

scholarly journals Thermodynamics of Dyonic NUT Charged Black Holes with entropy as Noether charge

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Niloofar Abbasvandi ◽  
Masoumeh Tavakoli ◽  
Robert B. Mann
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Free Energy ◽  
Phase Behaviour ◽  
Charged Black Holes ◽  
Black Hole Spacetimes ◽  
Horizon Entropy ◽  
Transition Structures ◽  
Extremal Black Holes

Abstract We investigate the thermodynamic behaviour of Lorentzian Dyonic Taub-NUT Black Hole spacetimes. We consider two possibilities in their description: one in which their entropy is interpreted to be one quarter of the horizon area (the horizon entropy), and another in which the Misner string also contributes to the entropy (the Noether charge entropy). We find that there can be as many as three extremal black holes (or as few as zero) depending on the choice of parameters, and that the dependence of the free energy on temperature — and the resultant phase behaviour — depends very much on which of these situations holds. Some of the phase behaviour we observe holds regardless of which interpretation of the entropy holds. However another class of phase transition structures occurs only if the Noether charge interpretation of the entropy is adopted.

scholarly journals QUANTIZATION OF BLACK HOLES ENTROPY AND ITS COSMOLOGICAL CONSEQUENCES

2013 ◽  
Vol 28 (16) ◽  
pp. 1350066 ◽  
Author(s):  
G. CRISTOFANO ◽  
G. MAIELLA ◽  
C. STORNAIOLO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Energy Levels ◽  
Hawking Temperature ◽  
Simple Interpretation ◽  
Level Number ◽  
Black Hole Temperature ◽  
Extremal Black Holes

Starting from a quantization relation for primordial extremal black holes with electric and magnetic charges, it is shown that their entropy is quantized. Furthermore, the energy levels spacing for such black holes is derived as a function of the level number n, appearing in the quantization relation. Some interesting cosmological consequences are presented for small values of n. By producing a mismatch between the mass and the charge, the black hole temperature is derived and its behavior investigated. Finally extending the quantum relation to Schwarzschild black holes their temperature is found to be in agreement with the Hawking temperature and a simple interpretation of the microscopic degrees of freedom of the black holes is given.

scholarly journals Dirac quasinormal modes of power-Maxwell charged black holes in Rastall gravity

2020 ◽  
Vol 35 (23) ◽  
pp. 2050193
Author(s):  
Cai-Ying Shao ◽  
Yu Hu ◽  
Yu-Jie Tan ◽  
Cheng-Gang Shao ◽  
Kai Lin ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Matrix Method ◽  
Quasinormal Modes ◽  
Einstein Gravity ◽  
Late Time ◽  
Charged Black Holes ◽  
The Matrix ◽  
Black Hole Solutions ◽  
Extremal Black Holes

In this paper, we study the quasinormal modes of the massless Dirac field for charged black holes in Rastall gravity. The spherically symmetric black hole solutions in question are characterized by the presence of a power-Maxwell field, surrounded by the quintessence fluid. The calculations are carried out by employing the WKB approximations up to the 13th-order, as well as the matrix method. The temporal evolution of the quasinormal modes is investigated by using the finite difference method. Through numerical simulations, the properties of the quasinormal frequencies are analyzed, including those for the extremal black holes. Among others, we explore the case of a second type of extremal black holes regarding the Nariai solution, where the cosmical and event horizon coincide. The results obtained by the WKB approaches are found to be mostly consistent with those by the matrix method. It is observed that the magnitudes of both real and imaginary parts of the quasinormal frequencies increase with increasing [Formula: see text], the spin–orbit quantum number. Also, the roles of the parameters [Formula: see text] and [Formula: see text], associated with the electric charge and the equation of state of the quintessence field, respectively, are investigated regarding their effects on the quasinormal frequencies. The magnitude of the electric charge is found to sensitively affect the time scale of the first stage of quasinormal oscillations, after which the temporal oscillations become stabilized. It is demonstrated that the black hole solutions for Rastall gravity in asymptotically flat spacetimes are equivalent to those in Einstein gravity, featured by different asymptotical spacetime properties. As one of its possible consequences, we also investigate the behavior of the late-time tails of quasinormal models in the present model. It is found that the asymptotical behavior of the late-time tails of quasinormal modes in Rastall theory is governed by the asymptotical properties of the spacetimes of their counterparts in Einstein gravity.

scholarly journals THE CARDY–VERLINDE FORMULA AND ASYMPTOTICALLY FLAT CHARGED BLACK HOLES

2001 ◽  
Vol 16 (19) ◽  
pp. 1263-1268 ◽  
Author(s):  
DONAM YOUM
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Casimir Effect ◽  
Higher Dimensions ◽  
Thermodynamic Quantities ◽  
Two Dimensional ◽  
Temperature Relation ◽  
Asymptotically Flat ◽  
Charged Black Holes ◽  
Verlinde Formula

We show that the modified Cardy–Verlinde formula without the Casimir effect term is satisfied by asymptotically flat charged black holes in arbitrary dimensions. Thermodynamic quantities of the charged black holes are shown to satisfy the energy-temperature relation of a two-dimensional CFT, which supports the claim in our previous work (Phys. Rev.D61, 044013, hep-th/9910244) that thermodynamics of charged black holes in higher dimensions can be effectively described by two-dimensional theories. We also check the Cardy formula for the two-dimensional black hole compactified from a dilatonic charged black hole in higher dimensions.

scholarly journals String analog of Reissner–Nordström black holes cannot be overcharged

2019 ◽  
Vol 34 (30) ◽  
pp. 1950248 ◽  
Author(s):  
Koray Düztaş ◽  
Mubasher Jamil
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Black Hole Thermodynamics ◽  
Drop Out ◽  
Charged Black Holes ◽  
The Third ◽  
Test Particles ◽  
Third Law ◽  
Extremal Black Holes

In this work, we attempt to overcharge extremal and nearly extremal charged black holes in string theory, known as the Garfinkle–Horowitz–Strominger solution. We first show that extremal black holes cannot be overcharged analogous to the case of Reissner–Nordström (RN) black holes. Contrary to their analog in general relativity, nearly extremal black holes can neither be overcharged beyond extremality, nor can they be driven to extremality by the interaction with test particles. Therefore, the analysis in this work also implies that the third law of black hole thermodynamics holds for the relevant charged black holes in string theory perturbed by test particles. This can be interpreted as a stronger version of the third law since one can drop out the continuity proviso for the relevant process.

scholarly journals A new spin on the Weak Gravity Conjecture

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Lars Aalsma ◽  
Alex Cole ◽  
Gregory J. Loges ◽  
Gary Shiu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mild Form ◽  
Black String ◽  
Charged Black Holes ◽  
Higher Derivative ◽  
Horizon Geometry ◽  
Weak Gravity ◽  
Extremal Black Holes ◽  
Kaluza Klein

Abstract The mild form of the Weak Gravity Conjecture states that quantum or higher-derivative corrections should decrease the mass of large extremal charged black holes at fixed charge. This allows extremal black holes to decay, unless protected by a symmetry (such as supersymmetry). We reformulate this conjecture as an integrated condition on the effective stress tensor capturing the effect of quantum or higher-derivative corrections. In addition to charged black holes, we also consider rotating BTZ black holes and show that this condition is satisfied as a consequence of the c-theorem, proving a spinning version of the Weak Gravity Conjecture. We also apply our results to a five-dimensional boosted black string with higher-derivative corrections. The boosted black string has a BTZ×S2 near-horizon geometry and, after Kaluza-Klein reduction, describes a four-dimensional charged black hole. Combining the spinning and charged Weak Gravity Conjecture we obtain positivity bounds on the five-dimensional Wilson coefficients that are stronger than those obtained from charged black holes alone.

scholarly journals Island in charged black holes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Yi Ling ◽  
Yuxuan Liu ◽  
Zhuo-Yu Xian
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Entanglement Entropy ◽  
Information Paradox ◽  
Extremal Surface ◽  
Charged Black Holes ◽  
Dimensional Spacetime ◽  
Black Hole Information ◽  
Extremal Black Holes

Abstract We study the information paradox for the eternal black hole with charges on a doubly-holographic model in general dimensions, where the charged black hole on a Planck brane is coupled to the baths on the conformal boundaries. In the case of weak tension, the brane can be treated as a probe such that its backreaction to the bulk is negligible. We analytically calculate the entanglement entropy of the radiation and obtain the Page curve with the presence of an island on the brane. For the near-extremal black holes, the growth rate is linear in the temperature. Taking both Dvali-Gabadadze-Porrati term and nonzero tension into account, we obtain the numerical solution with backreaction in four-dimensional spacetime and find the quantum extremal surface at t = 0. To guarantee that a Page curve can be obtained in general cases, we propose two strategies to impose enough degrees of freedom on the brane such that the black hole information paradox can be properly described by the doubly-holographic setup.

STATIC CHARGED DILATON BLACK HOLE SOLUTIONS IN NON-COMMUTATIVE SPACES

2007 ◽  
Vol 16 (01) ◽  
pp. 19-24
Author(s):  
M. R. SETARE ◽  
J. SADEGHI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Temperature ◽  
Dilaton Field ◽  
Commutative Case ◽  
Charged Black Holes ◽  
Extreme Black Hole ◽  
Dilaton Black Hole ◽  
Black Hole Solutions

Here we consider the black hole solutions which were obtained by Chan and Mann.1 These solutions represent static charged black holes with a dilaton field. Then we compute the corrections to the horizons and Hawking temperature of these black holes. These corrections stem from the space non-commutativity. We show that in a non-commutative case, temperature of extreme black hole, in contrast to that of the commutative case, is not zero.

scholarly journals Gravitational lensing effect on the Hawking radiation of dyonic black holes

2014 ◽  
Vol 11 (08) ◽  
pp. 1450074 ◽  
Author(s):  
Izzet Sakalli ◽  
Ali Ovgun ◽  
Seyedeh Fatemeh Mirekhtiary
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Refractive Index ◽  
Coordinate System ◽  
Gravitational Lensing ◽  
Hawking Radiation ◽  
Hawking Temperature ◽  
Tunneling Rate ◽  
Asymptotically Flat ◽  
Lensing Effect

In this paper, we analyze the Hawking radiation (HR) of a non-asymptotically flat (NAF) dyonic black hole (dBH) in four-dimensional (4D) Einstein–Maxwell–Dilaton (EMD) gravity by using one of the semiclassical approaches which is the so-called Hamilton–Jacobi (HJ) method. We particularly motivate on the isotropic coordinate system (ICS) of the dBH in order to highlight the ambiguity to be appeared in the derivation of the Hawking temperature (TH) via the HJ method. Besides, it will be shown that the ICS allows us to write the metric of the dBH in form of the Fermat metric, which renders possible of identification of the refractive index (n) of the dBH. It is unraveled that the value of n and therefore the gravitational lensing effect is decisive on the tunneling rate of the HR. We also uncloak how one can resolve the discrepancy about the TH of the dBH in spite of that lensing effect.

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