Kerr Black Holes within a Modified Theory of Gravity

Abstract

The Kerr black hole is studied within a modified theory of gravity, which adds the effects of vacuum fluctuations near a black hole. These vacuum fluctuations are treated as a dark energy. A parameter is introduced to account for these fluctuations. It is zero for the standard theory and acquires a maximal value, just before there would be no event horizon. The existence of an event horizon not only depends on the value of this parameter, but also on the spin of the black hole. In addition, we study the existence of a light-ring. We also elaborate on the relation of the appearance and vanishing of the event horizon and light-ring to phase transitions.

Axial ring‐down modes in general relativity and in its pseudo‐complex extension

“…The expression of m ( r ) guaranties that for a > 0 ( a is the Kerr rotational parameter with 0 ≤ a ≤ 1) there is no event‐horizon and only at a = 0 there is still one at . This is the latest form as used in pc‐GR (Hess 2019, 2020; Hess & López‐Moreno 2019b). Arbitrary values between 0 and 1 were also considered in Hess & López‐Moreno (2019b)), were the transition from GR and pc‐GR was studied and related to a phase transition.…”

“…This is the latest form as used in pc‐GR (Hess 2019, 2020; Hess & López‐Moreno 2019b). Arbitrary values between 0 and 1 were also considered in Hess & López‐Moreno (2019b)), were the transition from GR and pc‐GR was studied and related to a phase transition. Other dependencies on r can also be used as can be found in other contributions in this volume.…”

“…In Hess & López‐Moreno (2019a)), the parameter n = 3 was used, which had to be modified later on to n = 4 (Hess 2019, 2020; Hess & López‐Moreno 2019b), due to the observation made in Nielsen & Birnholz (2018, 2019)). In this contribution, a different, improved asymptotic limit for the gravitational wave solution is introduced.…”

A review on algebraic extensions in general relativity

“…In Boller et al (2019) and Hess et al (2019), the most recent compilation of results on the accretion disks is published, predicting a dark ring followed by a bright one in the light emission of such an accretion disk. In Hess (2019, 2020) and Hess & López‐Moreno (2019), reviews on the theory can be found.…”

Rotation Effects in Relativity

“…Dymnikova and Galaktionov [25] consider a model of nonlinear electrodynamics minimally coupled to gravity and study the dynamics of electromagnetic fields of rotating electrically charged black holes. Hess and López-Moreno [26] focus on another model of modified gravity, the so-called pseudo-complex General Relativity and, in this context, they study Kerr black hole in presence of vacuum fluctuations that are determined by the modified gravity model.…”