Hairy black holes by gravitational decoupling

Abstract

Black holes with hair represented by generic fields surrounding the central source of the vacuum Schwarzschild metric are examined under the minimal set of requirements consisting of i) the existence of a well defined event horizon and ii) the strong or dominant energy condition for the hair outside the horizon. We develop our analysis by means of the gravitational decoupling approach. We find that trivial deformations of the seed Schwarzschild vacuum preserve the energy conditions and provide a new mechanism to evade the no-hair theorem based on a primary hair associated with the charge generating these transformations. Under the above conditions i) and ii), this charge consistently increases the entropy from the minimum value given by the Schwarzschild geometry. As a direct application, we find a non-trivial extension of the Reissner-Nordström black hole showing a surprisingly simple horizon. Finally, the non-linear electrodynamics generating this new solution is fully specified.

Gravitational Decoupling in Higher Order Theories

“…This would be particularly interesting for studying hairy black holes, that is, black holes surrounded by scalar hair, as has been done recently in Ref. [59] in GR.…”

Gravitationally decoupled anisotropic solution using polytropic EoS in the framework of 5D Einstein–Gauss–Bonnet Gravity

“…Then, it may not be possible to embed the stellar compact object to vacuum space-time. But, if we assume that new contributions arising from θ μν are confined within the stellar interior [24,28], then the stellar compact object will remain embedded into a true Boulware-Deser vacuum space-time (52). Now we the fix easily the arbitrary constant parameters by joining of the interior (51) and exterior (52) spacetimes across the boundary.…”

“…But, if we assume that new contributions arising from θ μν are confined within the stellar interior [24,28], then the stellar compact object will remain embedded into a true Boulware-Deser vacuum space-time (52). Now we the fix easily the arbitrary constant parameters by joining of the interior (51) and exterior (52) spacetimes across the boundary. To do this, we consider the manifolds which have the boundaries defined by the time-like hypersurfaces…”

Minimally deformed anisotropic stars by gravitational decoupling in Einstein–Gauss–Bonnet gravity

“…Besides, the MGD approach was discussed to study extensions of GR in a cosmological context [86]. Furthermore, some interesting works have been published in the context of black hole solutions in 2+1 and 3+1 dimensions [87][88][89][90][91][92], what is more, recently new hairy black hole solutions have been found in [93] and also an algorithm has been developed to convert any non-rotating black hole spacetime into a rotating one [94,95]. Motivated by the preceding discussion, our goal in this article is to apply the MGD approach to solve the EGB field equations for a gravitational source, and then find a physically acceptable solution that represents the behavior of compact objects.…”