Superradiance and stability of the regularized 4D charged Einstein-Gauss-Bonnet black hole

Abstract

We investigated the superradiance and stability of the regularized 4D charged Einstein-Gauss-Bonnet black hole which is recently inspired by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)]. We found that the positive Gauss-Bonnet coupling constant α enhances the superradiance, while the negative α suppresses it. The condition for superradiant instability is proved. We also worked out the quasinormal modes (QNMs) of the charged Einstein-Gauss-Bonnet black hole and found that the real part of all the QNMs does not satisfy the superradiance condition and the imaginary parts are all negative. Therefore this black hole is stable. When α makes the black hole extremal, there are normal modes.

The correspondence between shadow and test field in a four-dimensional charged Einstein–Gauss–Bonnet black hole

“…Its specific values are calculated and listed in Table 1. As described in [80][81][82], α cannot be too negative, because the metric function may not be real inside the event horizon when α is too negative. The observational constraints on the coupling parameter α was found in [84].…”

Collapsing dust thin shells in Einstein–Gauss–Bonnet gravity

“…As a result of that proposal, the solution has regained widespread attention, and various properties of the 4D EGB solutions were considered within a short period time. For example, gravitational collapse was considered in [3], the generalization of the original solution [1] was studied in [4][5][6][7][8], black hole thermaldynamics was investigated in [9,10], gravitational lensing and shadow were considered in [5,6,[11][12][13], quasinormal modes and stability were showed in [14][15][16], the electromagnetic radiation properties of thin accretion disk around black hole were explored in [17], while the Hawking radiation and black hole evaporation were showed in [18,19] respectively. As research progresses, the validity of 4D EGB gravity is being questioned [20][21][22][23][24][25][26][27].…”

Polarized image of an equatorial emitting ring around a 4D Gauss-Bonnet black hole

“…Although there are some criticisms on this naive 4D theory of Gravity including its the regularization scheme [29][30][31], a well-defined theory is proposed to serve as a consistent realization of the 4D Einstein-Gauss-Bonnet gravity where there exist two dynamical degrees of freedom with breaking the temporal diffeomorphism invariance [32]. It is fortunate that the black hole solution obtained by the naive regularization [28] is confirmed as an exact solution in this full theory [32], which has greatly contributed to the study of the Einstein-Gauss-Bonnet gravity in the 4D spacetime on various aspects [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. In this paper, we will study the polarization image of an equatorial synchrotron emitting ring around the 4D Gauss-Bonnet black hole black hole [28] and to see the effects of Gauss-Bonnet parameter on the polarization image of emitting ring.…”