Hairy rotating black holes in cubic Galileon theory

Aelst, Karim Van; Gourgoulhon, Éric; Grandclément, Philippe; Charmousis, Christos

doi:10.1088/1361-6382/ab6391

Cited by 38 publications

(55 citation statements)

References 148 publications

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“…In order to bring light to this issue, one must clearly include metric contributions that are not circular. Signs of non-circularity have also been found numerically in the case of a DGP Horndeski rotating black hole [65]. Breaking the circularity hypothesis constitutes a milder approach to the one concluded in [64], where it is claimed that the related spinning black hole should break either the stationarity or axisymmetry hypothesis (or both).…”

Section: Jhep01(2021)018mentioning

confidence: 82%

Disforming the Kerr metric

Anson

Babichev

Charmousis

et al. 2021

J. High Energ. Phys.

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Starting from a recently constructed stealth Kerr solution of higher order scalar tensor theory involving scalar hair, we analytically construct disformal versions of the Kerr spacetime with a constant degree of disformality and a regular scalar field. While the disformed metric has only a ring singularity and asymptotically is quite similar to Kerr, it is found to be neither Ricci flat nor circular. Non-circularity has far reaching consequences on the structure of the solution. As we approach the rotating compact object from asymptotic infinity we find a static limit ergosurface similar to the Kerr spacetime with an enclosed ergoregion. However, the stationary limit of infalling observers is found to be a timelike hypersurface. A candidate event horizon is found in the interior of this stationary limit surface. It is a null hypersurface generated by a null congruence of light rays which are no longer Killing vectors. Under a mild regularity assumption, we find that the candidate surface is indeed an event horizon and the disformed Kerr metric is therefore a black hole quite distinct from the Kerr solution.

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Section: Jhep01(2021)018mentioning

confidence: 82%

Disforming the Kerr metric

Anson

Babichev

Charmousis

et al. 2021

J. High Energ. Phys.

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“…We remark that one can verify that the remaining equations vanish identically, E ϕ r = E t r = E ϕ θ = E t θ = 0, the circularity condition being satisfied. As such, the employed ansatz is consistent, a fact which is not a priori guaranteed (see [32] for a discussion in an Einstein-scalar field model which leads to a non-circular metric form).…”

Section: The Numerical Approachmentioning

confidence: 99%

Spinning black holes in shift-symmetric Horndeski theory

Delgado

Herdeiro

Radu

2020

J. High Energ. Phys.

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We construct spinning black holes (BHs) in shift-symmetric Horndeski theory. This is an Einstein-scalar-Gauss-Bonnet model wherein the (real) scalar field couples linearly to the Gauss-Bonnet curvature squared combination. The BH solutions constructed are stationary, axially symmetric and asymptotically flat. They possess a non-trivial scalar field outside their regular event horizon; thus they have scalar hair. The scalar "charge" is not, however, an independent macroscopic degree of freedom. It is proportional to the Hawking temperature, as in the static limit, wherein the BHs reduce to the spherical solutions found by Sotirou and Zhou. The spinning BHs herein are found by solving non-perturbatively the field equations, numerically. We present an overview of the parameter space of the solutions together with a study of their basic geometric and phenomenological properties. These solutions are compared with the spinning BHs in the Einstein-dilaton-Gauss-Bonnet model and the Kerr BH of vacuum General Relativity. As for the former, and in contrast with the latter, there is a minimal BH size and small violations of the Kerr bound. Phenomenological differences with respect to either the former or the latter, however, are small for illustrative observables, being of the order of a few percent, at most.

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“…Especially, the presence of the drdt term also leads to the lack of circularity in the disformal Kerr spacetime [22,23]. It is different from that in the usual Kerr spacetime in general relativity because the Kerr spacetime is circular, i.e., the spacetime can be foliated by 2-surfaces (called meridional surfaces) everywhere orthogonal to the Killing field ξ = ∂ t and η = ∂ ψ [36][37][38]. The lack of circularity modifies the structure of the black hole horizons so that the horizons depend on the polar angle θ and cannot be given by r = const in Boyer-Lindquist coordinates, and then the corresponding surface gravity is no longer a constant [22,23].…”

Section: Equation Of Motion For the Photons In The Rotating Non-stealmentioning

confidence: 99%

“…where the matrix e ν μ meets g μν e μ α e νβ = ηαβ , and ηαβ is the usual Minkowski metric. For an asymptotically flat stationary spacetime (4), it is convenient to choose a decomposition [38][39][40][41][42][43][44][45][46][47][48][49][50][51]…”

Section: Shadow Of the Disformal Kerr Black Hole In Quadratic Dhost Tmentioning

confidence: 99%

“…In general, it is very difficult to obtain exact solutions for black holes in alternative theories of gravity because the field equations become more complicated. However, some new black hole solutions in the DHOST theories have emerged these last years [14][15][16][17][18][19][20][21]. These solutions can be classified as the stealth solutions and the non-stealth solutions.…”

Section: Introductionmentioning

confidence: 99%

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Shadow of a disformal Kerr black hole in quadratic degenerate higher-order scalar–tensor theories

2020

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We have studied the shadow of a disformal Kerr black hole with an extra deformation parameter, which belongs to non-stealth rotating solutions in quadratic degenerate higher-order scalar–tensor (DHOST) theory. Our result show that the size of the shadow increases with the deformation parameter for the black hole with arbitrary spin parameter. However, the effect of the deformation parameter on the shadow shape depends heavily on the spin parameter of black hole and the sign of the deformation parameter. The change of the shadow shape becomes more distinct for the black hole with the more quickly rotation and the more negative deformation parameter. Especially, for the near-extreme black hole with negative deformation parameter, there exist a “pedicel”-like structure appeared in the shadow, which increases with the absolute value of deformation parameter. The eyebrow-like shadow and the self-similar fractal structures also appear in the shadow for the disformal Kerr black hole in DHOST theory. These features in the black hole shadow originating from the scalar field could help us to understand the non-stealth disformal Kerr black hole and quadratic DHOST theory.

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Hairy rotating black holes in cubic Galileon theory

Cited by 38 publications

References 148 publications

Disforming the Kerr metric

Disforming the Kerr metric

Spinning black holes in shift-symmetric Horndeski theory

Shadow of a disformal Kerr black hole in quadratic degenerate higher-order scalar–tensor theories

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