Instability and no-hair paradigm in d-dimensional charged-AdS black holes

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

doi:10.1016/j.nuclphysb.2020.115185

Cited by 19 publications

(3 citation statements)

References 56 publications

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“…Note that one cannot merely extract the hair solutions, claiming that the NTH is violated, since the stability status of the hairy solution is of high importance and deserves a deep analysis. Actually, if it suffers from instability, then the hair parameter will not coexist with the main parameters involved in the metric and thereby NHT remains valid [119]. The significant of NHT is that, unlike what GTR teached us, if BHs have hair, then we would need to change standard GTR 2 [122].…”

Section: Jcap09(2021)028mentioning

confidence: 99%

No-hair theorem in the wake of Event Horizon Telescope

Khodadi

Lambiase²,

Mota³

2021

J. Cosmol. Astropart. Phys.

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Thanks to the release of the extraordinary EHT image of shadow attributed to the M87* supermassive black hole (SMBH), we have a novel window to assess the validity of fundamental physics in the strong-field regime. Motivated by this, we consider Johannsen & Psaltis metric parameterized by mass, spin, and an additional dimensionless hair parameter . This parametric framework in the high rotation regimes provides a well-behaved bed to the strong-gravity test of the no-hair theorem (NHT) using the EHT data. Incorporating the into the standard Kerr spacetime enrich it in the sense that, depending on setting the positive and negative values for that, we deal with alternative compact objects: deformed Kerr naked singularity and Kerr BH solutions, respectively. Shadows associated with these two possible solutions indicate that the deformation parameter affects the geometry shape of standard shadow such that it becomes more oblate and prolate with < 0 and > 0, respectively. By scanning the window associated with three shadow observables oblateness, deviation from circularity, and shadow diameter, we perform a numerical analysis within the range a * = 0.9 ∓ 0.1 of the dimensionless rotation parameter, to find the constraints on the hair parameter in both possible solutions. For both possible signs of , we extract a variety of upper bounds that are in interplay with a * . Although by approaching the rotation parameters to the extreme limit, the allowable range of both hair parameters becomes narrower, the hairy Kerr BH solution is a more promising candidate to play the role of the alternative compact object instead of the standard Kerr BH. The lack of tension between hairy Kerr BH with the current observation of the EHT shadow of the M87* SMBH carries this message that there is the possibility of NHT violation.

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Section: Jcap09(2021)028mentioning

confidence: 99%

No-hair theorem in the wake of Event Horizon Telescope

Khodadi

Lambiase²,

Mota³

2021

J. Cosmol. Astropart. Phys.

Self Cite

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“…Recent studies show that spontaneous scalarization could exists typically in the models containing non-minimally coupling of a real scalar field to the source terms which could either be the geometric invariant sources such as the Ricci scalar, Gauss-Bonnet, Chern-Simons invariant [32][33][34][35][36][37][38][39][40][41][42][43][44] or the matter invariant sources such as Maxwell invariant in Einstein-Maxwell-scalar (EMS) theory [45][46][47][48][49][50][51] and Einstein-Maxwell-vector model [52]. The successful observation of gravitational waves [53][54][55] and the black hole shadow [56][57][58] have pushed the research and theoretical detection of black holes into a new era providing a new window to test the characteristics of black holes, thus it is necessary to carefully study the physics on hairy black holes such as metrics, the dynamic process of formation and evolution, and use the observation to test no-hair theorem or constraint the families of black holes [59,60].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Anti-de Sitter black holes in Einstein-Maxwell-dilaton theory

Zhang,

Liu,

Liu

et al. 2021

Preprint

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We study the nonlinear evolution of the spherical symmetric black holes under a small neutral scalar field perturbation in Einstein-Maxwell-dilaton theory with coupling function f (φ) = e −bφ in asymptotic anti-de Sitter spacetime. The non-minimal coupling between scalar and Maxwell fields allows the transmission of the energy from the Maxwell field to the scalar field, but also behaves as a repulsive force for the scalar. The scalar field oscillates with damping amplitude and converges to a final value by a power law. The irreducible mass of the black hole increases abruptly at initial times and then saturates to the final value exponentially. The saturating rate is twice the decaying rate of the dominant mode of the scalar. The effects of the black hole charge, the cosmological constant and the coupling parameter on the evolution are studied in detail. When the initial configuration

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“…Refs. [224][225][226][227][228][229][230]), where the resulting superradiant timescale can be significantly shorter, and thereby potentially leading to more optimistic results in the context of our work. For example, superradiance effects are strongly amplified for rotating dilatonic BHs in compactified higher dimensions [224].…”

Section: Discussionmentioning

confidence: 93%

Superradiance evolution of black hole shadows revisited

Roy,

Vagnozzi,

Visinelli

2021

Preprint

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Black hole (BH) shadows can be used to probe new physics in the form of ultra-light particles via the phenomenon of superradiant instability. By directly affecting the BH mass and spin, superradiance can lead to a time evolution of the BH shadow, which nonetheless has been argued to be unobservable through Very Long Baseline Interferometry (VLBI) over realistic observation timescales. We revisit the superradiance-induced BH shadow evolution including the competing effects of gas accretion and gravitational wave (GW) emission and, as a first step towards modelling realistic new physics scenarios which predict the existence of multiple ultra-light species, we study the system in the presence of two ultra-light bosons, whose combined effect could help reducing the shadow evolution timescale. We find that accretion and GW emission play a negligible role in our results (justifying previous simplified analyses), and that contrary to our intuition the inclusion of an additional ultra-light boson does not shorten the BH shadow evolution timescale and hence improve detection prospects. However, we point out an important subtlety concerning the observationally meaningful definition of the superradiance-induced BH shadow evolution timescale, which reduces the latter by about an order of magnitude, opening up the possibility of observing the superradiance-induced BH shadow evolution with upcoming VLBI arrays, provided angular resolutions just below the µas level can be reached. As a concrete example, we show that the angular size of the shadow of SgrA * can change by up to 0.6 µas over a period as short as 16 years, which further strengthens the scientific case for targeting the shadow of SgrA * with next-generation VLBI arrays.

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Instability and no-hair paradigm in d-dimensional charged-AdS black holes

Cited by 19 publications

References 56 publications

No-hair theorem in the wake of Event Horizon Telescope

No-hair theorem in the wake of Event Horizon Telescope

Evolution of Anti-de Sitter black holes in Einstein-Maxwell-dilaton theory

Superradiance evolution of black hole shadows revisited

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