Superradiant instability and asymptotically AdS hairy black holes in $F(R)$-charged scalar field theory

Rahmani, A.; Honardoost, M.; Sepangi, H. R.

doi:10.48550/arxiv.1810.03080

Cited by 3 publications

(10 citation statements)

References 75 publications

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“…We define the superradiant regime as the onset of Re(ω) = Re(ω) + qC − qQ/r + < 0 which implies Im(ω) > 0 and the exponential growth of the scalar field wave function with time, leading to black hole instability. To analyze the instability numerically, we use the shooting method [47], integrating Eq. ( 12) numerically from r + to L, for which the base values are given by equations (15).…”

Section: Amentioning

confidence: 99%

“…In this section we study the endpoint of superradiance instability and show that the result is a small hairy black hole which is stable at T = T c . To investigate the system stability, we first consider its time evolution by assuming time dependence of the field variables in addition to radial dependency and derive perturbation equations by linearly perturbing the system around static solutions [47].…”

Section: End Point Of Superradiant Instability and Stability Analysismentioning

confidence: 99%

“…Let us now linearly perturb the system around static solutions as V (r, t) = V + δV (r, t), where V and δV (r, t) show static solutions and perturbations, and similarly for other field variables and substitute them in equations (26)(27)(28)(29)(30)(31)(32). Now, defining δΨ = δu + iδ ẇ and eliminating metric variables, perturbation equations are obtained as two dynamical equations and a constraint [47]…”

Section: B Perturbation Equationsmentioning

confidence: 99%

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Final state of instabilities in Born-Infeld black holes

Rahmani,

Honardoost,

Sepangi

2020

Preprint

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We study two types of linear instabilities in Einstein-Born-Infeld-scalar field theory and show that small Born-Infeld (BI) black holes suffer from superradiant instability within a particular range of frequencies; the larger the BI coupling parameter, the slower the growth rate of the instability. It is predicted that a small BI black hole decays into a small hairy black hole that has a charged scalar condensate floating near the horizon. We numerically show that there is a phase transition between hairy and BI black holes. The metric solution shows the existence of a hairy black hole for T < Tc and a BI black hole for T > Tc. In addition, the BI black hole will suffer from tachyonic mass, resulting in a near horizon scalar condensation instability, which is related to a planar hairy black hole. We show that the BI coupling parameter has a direct relation to the critical temperature in the small hairy black hole framework. This is not true for planar hairy black holes where a larger BI coupling parameter leads to a smaller critical temperature. Finally, it is shown that a small hairy black hole is stable at the critical temperature so it can be considered as the end point of superradiant instability.

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Section: Amentioning

confidence: 99%

Section: End Point Of Superradiant Instability and Stability Analysismentioning

confidence: 99%

Section: B Perturbation Equationsmentioning

confidence: 99%

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Final state of instabilities in Born-Infeld black holes

Rahmani,

Honardoost,

Sepangi

2020

Preprint

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“…Technically, investigation of a black hole stability is an arduous problem due to non-linear partial differential equations resulting from field equations. However, recent improvements in numerical methods have revived the issue once more and attracted considerable attentions in the context of alternative theories of gravity [5,6,8].…”

Section: Introductionmentioning

confidence: 99%

“…The question then arises as to what is expected as the final fate of an unstable black hole? A stable hairy black hole [5,6,28] or an explosion event called bosenova [30,31] are two possible candidates describing the final state of a superradiantly unstable system both in GR or alternatively in F (R) theories of gravity [8].…”

Section: Introductionmentioning

confidence: 99%

Thermal phase transition in F(R) -charged AdS4 scalar theory

2020

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We investigate instabilities of F (R)-charged AdS4 black holes by a massive charged scalar field in a linear perturbation regime. We study tachyonic instabilities as the near horizon scalar condensation in a model of F (R) gravity with planar horizon and investigate properties of possible phase transitions. The results show that such transitions are sensitive to the first derivative of F (R) with respect to R in that the larger its value, the higher the critical temperature, thus resulting in a new generation of high-temperature superconductors. Also, for a certain range of parameters, F (R)charged AdS4 black holes suffer from superradiant instability. We consider the effects of the scalar mass and charge on such instabilities and conclude that RN black holes decay into small hairy black holes that have a charged scalar condensate floating near the horizon. It is shown that the existence of phase transition at the critical temperature leading to a hairy black hole solution emerges for T < Tc, while RN black holes exist for T > Tc. The effect of F (R) on the critical temperature is subsequently investigated in the case of superradiant instability, showing that higher critical temperatures would be possible in F (R) gravity. We also check the stability of hairy black holes and show that the resulting hairy solution can be considered as a possible end point of superradiant instability of a small charged black hole.

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Weak cosmic censorship with pressure and volume in charged anti-de Sitter black hole under charged scalar field

Gwak

2019

J. Cosmol. Astropart. Phys.

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We investigate the weak cosmic censorship conjecture for Kerr-Sen black holes, which are solutions to the four-dimensional low-energy effective field theory for the heterotic string theory, based on the scattering of a charged scalar field. When the fluxes of the scalar field are assumed to transfer its conserved quantities to the black hole, extremal and near-extremal black holes cannot be over-spun and over-charged in their first-order variations, which is sufficient to conclude that the weak cosmic censorship conjecture is valid for Kerr-Sen black holes. We confirm our conclusion by relating it to the first, second, and third laws of thermodynamics. 1

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Superradiant instability and asymptotically AdS hairy black holes in $F(R)$-charged scalar field theory

Cited by 3 publications

References 75 publications

Final state of instabilities in Born-Infeld black holes

Final state of instabilities in Born-Infeld black holes

Thermal phase transition in F(R) -charged AdS4 scalar theory

Weak cosmic censorship with pressure and volume in charged anti-de Sitter black hole under charged scalar field

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