scholarly journals Overspinning Kerr-MOG black holes by test fields and the third law of black hole dynamics

2020 ◽  
Vol 80 (1) ◽  
Author(s):  
Koray Düztaş
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Velocity ◽  
Weak Form ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Test Field ◽  
Naked Singularities ◽  
The Third ◽  
Third Law

AbstractWe evaluate the validity of the weak form of the cosmic censorship conjecture and the third law of black hole dynamics for Kerr-MOG black holes interacting with test scalar fields. Ignoring backreaction effects, we first show that both extremal and nearly extremal Kerr-MOG black holes can be overspun into naked singularities by test fields with a frequency slightly above the superradiance limit. In addition, nearly extremal Kerr-MOG black holes can be continuously driven to extremality by test fields. Next, we employ backreaction effects based on the argument that the angular velocity of the event horizon increases before the absorption of the test field. Incorporating the backreaction effects, we derive that the weak form of the cosmic censorship and the third law are both valid for Kerr-MOG black holes with a modification parameter $$\alpha \lesssim 0.03$$α≲0.03, which includes the Kerr case with $$\alpha =0$$α=0.

scholarly journals Overcharging dilaton black holes in (2 + 1) dimensions to extremality and beyond

2020 ◽  
Vol 17 (14) ◽  
pp. 2050207
Author(s):  
Koray Düztaş ◽  
Mubasher Jamil
Keyword(s):  
Black Holes ◽  
Weak Form ◽  
Cosmic Censorship ◽  
Black Hole Thermodynamics ◽  
Naked Singularities ◽  
The Third ◽  
Test Particles ◽  
Third Law ◽  
Dilaton Black Holes ◽  
Extremal Black Holes

We test whether static charged dilaton black holes in [Formula: see text] dimensions can be turned into naked singularities by sending in test particles from infinity. We derive that overcharging is possible and generic for both extremal and nearly extremal black holes. Our analysis also implies that nearly extremal charged dilaton black holes can be continuously driven to extremality and beyond, unlike nearly extremal Ban̆ados–Teitelboim–Zanelli, Kerr and Reissner–Nordström black holes which are overspun or overcharged by a discrete jump. Thus, the weak form of the cosmic censorship conjecture and the third law of black hole thermodynamics are both violated in the interaction of charged dilaton black holes in [Formula: see text] dimensions, with test particles. We also derive that there exist no points, where the heat capacity vanishes or diverges in the transition from black holes to naked singularities. The phase transitions that could potentially prevent the formation of naked singularities do not occur.

scholarly journals Can Naked Singularities Exist Without Violating The Laws of Black Hole Thermodynamics?

2021 ◽  
Vol 19 ◽  
pp. 204-207
Author(s):  
Amal Pushp
Keyword(s):  
Black Hole ◽  
Cosmic Censorship ◽  
Black Hole Thermodynamics ◽  
Surface Gravity ◽  
Extremal Black Hole ◽  
Naked Singularities ◽  
The Third ◽  
Physical Singularity ◽  
Third Law ◽  
Cosmic Censorship Conjecture

According to the cosmic censorship conjecture, it is impossible for nature to have a physical singularity without a horizon because if it were to arise in any formalism, for instance as an extremal black hole (Kerr or Reissner-Nordstrom) then the surface gravity κ = 0, which is a strict violation of the third law of black hole thermodynamics. In this paper we explore whether a true singularity can exist without defying this law.

scholarly journals Over-spinning Kerr–Sen black holes with test fields

2019 ◽  
Vol 28 (02) ◽  
pp. 1950044 ◽  
Author(s):  
Koray Düztaş
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gordon Equation ◽  
Naked Singularity ◽  
Weak Form ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Extremal Black Hole ◽  
Klein Gordon ◽  
Fermionic Fields

In this work, we investigate validity of the weak form of the cosmic censorship conjecture in the interaction of Kerr–Sen black holes with neutral test fields. Previous studies of the Klein–Gordon equation on Kerr–Sen background imply that superradiance occurs for scalar fields. We show that scalar fields can overspin a nearly extremal black hole into a naked singularity, but the modes that could overspin an extremal black hole are not absorbed due to superradiance. From Kerr analogy one can naively expect superradiance to be absent for fermionic fields. In such a case overspinning becomes generic and also applies to extremal Kerr–Sen black holes. This robust violation of cosmic censorship cannot be fixed by backreaction effects which are ignored in this work. These results are analogous to the Kerr case.

scholarly journals BLACK HOLES AND THE THIRD LAW OF THERMODYNAMICS

2004 ◽  
Vol 13 (04) ◽  
pp. 739-770 ◽  
Author(s):  
F. BELGIORNO ◽  
M. MARTELLINI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Second Law Of Thermodynamics ◽  
Temperature Limit ◽  
Black Hole Thermodynamics ◽  
Zero Temperature ◽  
The Third ◽  
Third Law Of Thermodynamics ◽  
Third Law ◽  
Extremal Black Holes

We discuss in the framework of black hole thermodynamics some aspects relative to the third law in the case of black holes of the Kerr–Newman family. In the light of the standard proof of the equivalence between the unattainability of the zero temperature and the entropic version of the third law it is remarked that the unattainability has a special character in black hole thermodynamics. Also the zero temperature limit which obtained in the case of very massive black holes is discussed and it is shown that a violation of the entropic version in the charged case occurs. The violation of the Bekenstein–Hawking law in favour of zero entropy SE=0 in the case of extremal black holes is suggested as a natural solution for a possible violation of the second law of thermodynamics. Thermostatic arguments in support of the unattainability are explored, and SE=0 for extremal black holes is shown to be again a viable solution. The third law of black hole dynamics by W. Israel is then interpreted as a further strong corroboration to the picture of a discontinuity between extremal states and non-extremal ones.

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 EXTREMAL BLACK HOLES AND THE LIMITS OF THE THIRD LAW

2001 ◽  
Vol 10 (01) ◽  
pp. 33-39 ◽  
Author(s):  
STEFANO LIBERATI ◽  
TONY ROTHMAN ◽  
SEBASTIANO SONEGO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Thermodynamics ◽  
Quantum Field ◽  
Semiclassical Theory ◽  
Zero Temperature ◽  
The Third ◽  
The Status ◽  
Third Law ◽  
Extremal Black Holes

Recent results of quantum field theory on a curved spacetime suggest that extremal black holes are not thermal objects and that the notion of zero temperature is ill-defined for them. If this is correct, one may have to go to a full semiclassical theory of gravity, including backreaction, in order to make sense of the third law of black hole thermodynamics. Alternatively it is possible that we shall have to drastically revise the status of extremality in black hole thermodynamics.

scholarly journals INSTABILITIES OF NAKED SINGULARITIES AND BLACK HOLE INTERIORS IN GENERAL RELATIVITY

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1578-1582 ◽  
Author(s):  
GUSTAVO DOTTI ◽  
REINALDO J. GLEISER ◽  
JORGE PULLIN ◽  
IGNACIO F. RANEA-SANDOVAL ◽  
HÉCTOR VUCETICH
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Recent Work ◽  
Kerr Black Hole ◽  
Cosmic Censorship ◽  
Negative Mass ◽  
Naked Singularities ◽  
Gravitational Perturbations ◽  
Inner Horizon

Metrics representing black holes in General Relativity may exhibit naked singularities for certain values of their parameters. This is the case for super-extremal (J2 > M > 0) Kerr and super-extremal (|Q| > M > 0) Reissner-Nördstrom spacetimes, and also for the negative mass Schwarzschild spacetime. We review our recent work where we show that these nakedly singular spacetimes are unstable under linear gravitational perturbations, a result that supports the cosmic censorship conjecture, and also that the inner stationary region beyond the inner horizon of a Kerr black hole (J2 < M) is linearly unstable.

scholarly journals A new touch temperature of the event horizon and Rindler horizon in the Kinnersley spacetime

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Jie Zhang ◽  
Menquan Liu ◽  
Zhie Liu ◽  
Shuzheng Yang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dispersion Relation ◽  
Event Horizon ◽  
Dynamical Equation ◽  
Radiation Temperature ◽  
The Third ◽  
Touch Point ◽  
Third Law Of Thermodynamics ◽  
Third Law

AbstractThe Kinnersley spacetime not only describes a non-spherical symmetric, non-stationary and accelerating black hole, but also can be used to explore the characteristics of collision of two black holes because it has two horizons: the Rindler horizon and the event horizon. Previous research shows Rindler horizon and the event horizon cannot touch due to violation of the third law of thermodynamics. By solving a fermion dynamical equation including the Lorentz dispersion relation, we obtain a modified radiation temperature at the event horizon of the black hole, as well as the colliding temperature at the touch point of Rindler horizon and the event horizon. We find the temperature at the touch point is not equal to zero if $${\dot{r}}_H\ne 0$$ r ˙ H ≠ 0 . This result indicates that the event horizon and Rindler horizon can collide without violation of the third law of thermodynamics when Lorentz dispersion relation is considered.

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