Nutty black holes in Galileon scalar-tensor gravity

Brandelet, Antoine; Brihaye, Yves; Delsate, Térence; Ducobu, Ludovic

doi:10.1142/s0217751x18501890

Cited by 3 publications

(4 citation statements)

References 23 publications

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“…Nutty-Hairy black holes in Einstein-Chern-Simons gravity were constructed in [29] and [21] for γ 2 = 0 and γ 1 = 0 respectively. Similar solutions within Einstein-Gauss-Bonnet (rather than Chern-Simons) gravity were obtained in [23]. The field equations are given by (2.4) and (2.5) with a different expression of T (I) µν which can be found in [21] with the same notations as in Sect.…”

Section: Resultsmentioning

confidence: 69%

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Hairy black holes, boson stars and non-minimal coupling to curvature invariants

Brihaye

Ducobu

2019

Physics Letters B

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The Einstein-Klein-Gordon Lagrangian is supplemented by a non-minimal coupling of the scalar field to specific geometric invariants : the Gauss-Bonnet term and the Chern-Simons term. The non-minimal coupling is chosen as a general quadratic polynomial in the scalar field and allows -depending on the parameters -for large families of hairy black holes to exist. These solutions are characterized, namely, by the number of nodes of the scalar function. The fundamental family encompasses black holes whose scalar hairs appear spontaneously and solutions presenting shift-symmetric hairs. When supplemented by a an appropriate potential, the model possesses both hairy black holes and non-topological solitons : boson stars. These latter exist in the standard Einstein-Klein-Gordon equations; it is shown that the coupling to the Gauss-Bonnet term modifies considerably their domain of classical stability.Abandonning the hypothesis of shift-symmetry, several groups [12], [13], [14] considered during the past years, new types of coupling terms between a scalar field and specific geometric invariants (essentially the Gauss-Bonnet term). In these models the occurrence of hairy black holes results from an unstable mode of the scalar field equation in the background of a vacuum metric (the probe limit). The interacting term of the scalar field with the curvature invariant plays a role of potential and the coupling constant the role of a spectral parameter. By continuity, the hairy black holes then exist as solutions of the full system. It is used to say that the hairy black holes appear through a spontaneous scalarization for a sufficiently large value of the coupling constant.In the present paper we will consider a model of scalar-tensor gravity encompassing the theories presenting a spontaneous scalarization and the shift-symmetry property. Families of classical solutions whose pattern extrapolates smoothly between shift-symmetric hairy black holes and spontaneous scalarized ones will be constructed . The type of structure found holds when coupling the scalar field to the Gauss-Bonnet invariant and to the Einstein-Chern-Simons invariant as well. All black holes solutions found are supported by the non-minimal coupling between the scalar field and the curvature invariant; however the field equations admit other types of solutions: boson stars. These regular solutions exist with a minimal coupling of scalar field to gravity but it will be shown that the non minimal coupling has important consequences on their stability properties.The paper is organized as follow : in Sect. 2 we present the model to be studied. Namely the Einstein-Klein-Gordon Lagrangian extended by a non-minimal coupling. We discuss the spherically symmetric ansatz and the general form of the field equations. Sect. 3 is devoted to the presentation of the hairy black holes occurring in the model. The boson stars are presented in Sect. 4 with an emphasis on the influence of the non-minimal coupling of the spectrum of the solutions. Conclusions are drawn in Sect. 5. S...

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Section: Resultsmentioning

confidence: 69%

“…Solutions corresponding to the "-" sign can be constructed as well (see e.g. [23]), forming a second branch whith higher mass. This branch, however is difficult to construct numerically.…”

Section: Fundamental Branchmentioning

confidence: 99%

Hairy black holes, boson stars and non-minimal coupling to curvature invariants

Brihaye

Ducobu

2019

Physics Letters B

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“…In these theories, it was shown that scalarized black holes exists for several choices of the non-minimal coupling function F (ψ) [30][31][32][33][34][35][36]. The first example was provided in [30,31] assuming a linear coupling (F (ψ) ∝ ψ).…”

Section: Introductionmentioning

confidence: 99%

Scalarized black holes in teleparallel gravity

Bahamonde

Ducobu

Pfeifer

2022

J. Cosmol. Astropart. Phys.

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Black holes play a crucial role in the understanding of the gravitational interaction. Through the direct observation of the shadow of a black hole by the event horizon telescope and the detection of gravitational waves of merging black holes we now start to have direct access to their properties and behaviour, which means the properties and behaviour of gravity. This further raised the demand for models to compare with those observations. In this respect, an important question regarding black holes properties is to know if they can support “hairs”. While this is famously forbidden in general relativity, in particular for scalar fields, by the so-called no-hair theorems, hairy black holes have been shown to exist in several class of scalar-tensor theories of gravity. In this article we investigate the existence of scalarized black holes in scalar-torsion theories of gravity. On one hand, we find exact solutions for certain choices of couplings between a scalar field and the torsion tensor of a teleparallel connection and certain scalar field potentials, and thus proof the existence of scalarized black holes in these theories. On the other hand, we show that it is possible to establish no-scalar-hair theorems similar to what is known in general relativity for other choices of these functions.

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“…In these theories, it was shown that scalarised black holes exists for several choices of the non-minimal coupling function F (ψ) [30][31][32][33][34][35][36]. The first example was provided in [30,31] assuming a linear coupling (F (ψ) ∝ ψ).…”

Section: Introductionmentioning

confidence: 99%

Scalarized Black Holes in Teleparallel Gravity

Bahamonde,

Ducobu,

Pfeifer

2022

Preprint

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Black holes play a crucial role in the understanding of the gravitational interaction. Through the direct observation of the shadow of a black hole by the event horizon telescope and the detection of gravitational waves of merging black holes we now start to have direct access to their properties and behaviour, which means the properties and behaviour of gravity. This further raised the demand for models to compare with those observations. In this respect, an important question regarding black holes properties is to know if they can support "hairs". While this is famously forbidden in general relativity, in particular for scalar fields, by the so-called no-hair theorems, hairy black holes have been shown to exist in several class of scalar-tensor theories of gravity. In this article we investigate the existence of scalarized black holes in scalar-torsion theories of gravity. On one hand, we find exact solutions for certain choices of couplings between a scalar field and the torsion tensor of a teleparallel connection and certain scalar field potentials, and thus proof the existence of scalarized black holes in these theories. On the other hand, we show that it is possible to establish no-scalar-hair theorems similar to what is known in general relativity for other choices of these functions.

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Nutty black holes in Galileon scalar-tensor gravity

Cited by 3 publications

References 23 publications

Hairy black holes, boson stars and non-minimal coupling to curvature invariants

Hairy black holes, boson stars and non-minimal coupling to curvature invariants

Scalarized black holes in teleparallel gravity

Scalarized Black Holes in Teleparallel Gravity

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