Scalar clouds and the superradiant instability regime of Kerr-Newman black hole

Abstract

In this paper, we study a physical system that is composed of massive charged scalar field linearly coupled to a charged rotating Kerr-Newman black hole. Given the parameters of black hole and a specific set of "quantum" numbers, the parameter space of the scalar field, which is a plane spanned by its mass and charge, is divided into five partitions by three simple constraint lines and the existence line of scalar clouds. The physical properties of the system in these partitions are presented. It is found that superradiant instability may be possibly caused only in two of the partitions. In particular, it is shown that both the mass and charge of the scalar clouds are bounded in a limited region. Our results may be used to rapidly judge the possible occurrence of superradiant instability and the existence of scalar clouds around a given black hole.

Superradiance in the BTZ black hole with Robin boundary conditions

“…Note that the reciprocal gamma function 1/Γ(z) is an entire function of z which has zeros at z ∈ Z − 0 [which correspond to the Dirichlet frequencies (14) and (15)]. Moreover, it tends to zero when Re[z] → +∞.…”

“…1, we verify that this mode is continuously connected, as a function of ζ, to the Dirichlet and Neumann n = 0 quasi-bound state modes of type L, Eqs. (14) and (16). For fixed RBC, all the other quasi-bound frequencies are such that Im[ω] < 0.…”

“…Much work has been devoted in the last decades towards understanding this instability, when the trapping is enforced by a mass term of the Bosonic field (see e.g. [3][4][5][6][7][8][9][10][11][12][13][14][15]). In particular, quite recently, interesting progress has been achieved towards understanding the end state of the superradiant instability of the Kerr BH [16,17], possible leading to an equilibrum state between the field and the (spun down) BH [18][19][20].…”

On-axis scattering of scalar fields by charged rotating black holes

“…The evolution and stability of scalar perturbations in Kerr-Newman background have already been studied [54][55][56][57][58]. Investigations concerning bound states formed of scalar fields (scalar clouds) around Kerr-Newman BHs have also been carried out [59][60][61]. As far as we are aware of, a study of the time-independent scattering of scalar fields by Kerr-Newman BHs is still lacking in the literature, and constitutes the aim of the present Letter.…”

Superradiant stability of mutated Reissner–Nordström black holes

“…Reissner-Nordström black holes are known to be superradiantly stable against perturbation by massive charged scalar fields [16][17][18][19] in the entire parameter space and does not lead to a black hole bomb, whereas, rotating black holes (Kerr black holes) are not stable against perturbations by massive bosonic fields [4,11,[20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Kerr-Newman black holes, on the other hand, are superradiantly unstable against perturbation by massive charged scalar field only when [34,35]). Charged black holes in string theory are also superradiantly stable against massive charged scalar perturbation [36].…”