Spinning-charged-hairy black holes in 5D Einstein gravity

Brihaye, Yves; Ducobu, Ludovic

doi:10.1103/physrevd.98.064034

Cited by 6 publications

(2 citation statements)

References 27 publications

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“…In this case, therefore, it is unclear how the instability of the Schwarzschild solution terminates. See [30][31][32][33][34][35][36][37] for additional recent work on eSTGB BH scalarisation.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features

Fernandes

Herdeiro

Pombo

et al. 2019

Class. Quantum Grav.

154

191

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Spontaneous scalarisation of electrically charged, asymptotically flat Reissner-Nordström black holes (BHs) has been recently demonstrated to occur in Einstein-Maxwell-Scalar (EMS) models. This phenomenon is allowed by a non-minimal coupling between the scalar and the Maxwell fields, and does not require non-minimal couplings of the scalar field to curvature invariants. EMS BH scalarisation presents a technical simplification over the BH scalarisation that has been conjectured to occur in extended Scalar-Tensor Gauss-Bonnet (eSTGB) models. It is then natural to ask: 1) how universal are the conclusions extracted from the EMS model? And 2) how much do these conclusions depend on the choice of the non-minimal coupling function? Here we address these questions by performing a comparative analysis of several different forms for the coupling function including: exponential, hyperbolic, power-law and a rational function (fraction) couplings. In all of them we obtain and study the domain of existence of fundamental, spherically symmetric, scalarised BHs and compute, in particular, their entropy. The latter shows that scalarised EMS BHs are always entropically preferred over the RN BHs with the same total charge to mass ratio q. This contrasts with the case of eSTGB, where for the same power-law coupling the spherical, fundamental scalarised BHs are not entropically preferred over the Schwarzschild solution. Also, while the scalarised solutions in the EMS model for the exponential, hyperbolic and power-law coupling are very similar, the rational function coupling leads to a transition in the domain of existence, by virtue of a pole in the coupling function, into a region of "exotic" solutions that violate the weak energy condition. Furthermore, fully non-linear dynamical evolutions of unstable RN BHs with different values of q are presented. These show: 1) for sufficiently small q, scalarised solutions with (approximately) the same q form dynamically; 2) for large q, spontaneous scalarisation visibly decreases q; thus evolutions are non-conservative; 3) despite the existence of non-spherical, static scalarised solutions, the evolution of unstable RN BHs under non-spherical perturbations leads to a spherical scalarised BH. arXiv:1902.05079v2 [gr-qc]

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Section: Introductionmentioning

confidence: 99%

Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features

Fernandes

Herdeiro

Pombo

et al. 2019

Class. Quantum Grav.

154

191

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“…This property is closely related to the Fermat's principle in flat spacetime that light propagates along the null trajectories of extreme time [40]. On the other side, Herdeiro and Radu constructed novel Kerr black holes with scalar hair [41,42], which are equilibrium states and may play an important role in realistic astrophysical processes [43][44][45][46][47][48]. In this work, we plan to extend the discussion of orbital period in [39,40] to kerr black holes with scalar field hair.…”

Section: Introductionmentioning

confidence: 99%

The extreme orbital period in scalar hairy kerr black holes

Peng

2019

Physics Letters B

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In a very interesting paper, Hod has proven that the equatorial null circular geodesic provides the extreme orbital period to circle a kerr black hole, which is closely related to the Fermat's principle.In the present paper, we extend the discussion to kerr black holes with scalar field hair. We show that the circle with the extreme orbital period is still identical to the null circular geodesic. Our analysis also implies that the Hod's theorem may be a general property in any axially symmetric spacetime with reflection symmetry on the equatorial plane.

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Kerr black holes with synchronised scalar hair and higher azimuthal harmonic index

2019

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Kerr black holes with synchronised scalar hair and azimuthal harmonic index m > 1 are constructed and studied. The corresponding domain of existence has a broader frequency range than the fundamental m = 1 family; moreover, larger ADM masses, M and angular momenta J are allowed. Amongst other salient features, non-uniqueness of solutions for fixed global quantities is observed: solutions with the same M and J co-exist, for consecutive values of m, and the ones with larger m are always entropically favoured. Our analysis demonstrates, moreover, the qualitative universality of various features observed for m = 1 solutions, such as the shape of the domain of existence, the typology of ergo-regions, and the horizon geometry, which is studied through its isometric embedding in Euclidean 3-space. IntroductionKerr black holes (BHs) with synchronised scalar hair [1] are a counterexample to the no-hair conjecture [2]see [3-5] for reviews -occurring in a simple and physically sound model: Einstein-(complex and massive-)Klein-Gordon theory. Many related solutions, relying on a similar synchronisation mechanism, have been found in the last few years, in different setups and approximations. An incomplete list of references, including also various studies of physical properties, is .These hairy BH solutions have a relation with the physical phenomenon of superradiance [67], from which they can form dynamically from the Kerr solution [45-47] -see also [54,57] for a discussion on the metastability of these solutions against superradiance. They also reduce to Kerr BHs and boson stars [68,69], in appropriate limits. Boson stars are a sort of gravitating soliton interpreted as a Bose-Einstein condensate of an ultra-light scalar field, that could be a dark matter candidate [70,71]. Moreover, the existence of the hairy BH solutions does not rely on particular choices of scalar field potentials that violate energy conditions, unlike other examples of asymptotically flat BHs with scalar hair, see e.g. [72,73]. Thus, besides the issue of the no-hair conjecture in BH physics, these hairy BHs contain different angles of interest.Kerr BHs with synchronised hair comprise a family that, besides the continuous parameters mass, angular momentum and Noether charge, is labelled by two discrete numbers: the azimuthal harmonic index of the scalar field m ∈ Z + and its node number n. Most of the studies of the solutions have focused on the fundamental solutions, n = 0, with the smallest value of m = 1. Recently, excited solutions (n = 0) have also been constructed [63]. Solutions with m > 1, on the other hand, have only been considered in the solitonic (boson star) limit [14,74], with the exception of the non-minimal model studied in [16]. The purpose of this work is to construct solutions with m > 1 in the minimal, simplest model, and to study some of the basic physical properties of these new solutions.

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Spinning-charged-hairy black holes in 5D Einstein gravity

Cited by 6 publications

References 27 publications

Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features

Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features

The extreme orbital period in scalar hairy kerr black holes

Kerr black holes with synchronised scalar hair and higher azimuthal harmonic index

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