Massive vector fields in Kerr-Newman and Kerr-Sen black hole spacetimes

Ramiro Cayuso,Leander Thiele,Aoibheann Margalit,David Kubizňák,Renato Gomes Souza,Finnian Gray,Oscar J.C Dias,Jorge E Santos

doi:10.1007/jhep04(2020)159

Abstract

The superradiant instability modes of ultralight massive vector bosons are studied for weakly charged rotating black holes in Einstein-Maxwell gravity (the Kerr- Newman solution) and low-energy heterotic string theory (the Kerr-Sen black hole). We show that in both these cases, the corresponding massive vector (Proca) equations can be fully separated, exploiting the hidden symmetry present in these spacetimes. The resultant ordinary differential equations are solved numerically to find the most unstable modes of the Proca field in the two backgrounds and compared to the vacuum (Kerr black hole) case.

Highlights

Dark matter candidates, e.g. [9]
That we have presented and separated the Proca equations for the Kerr-Newman and Kerr-Sen black holes we can turn to studying the consequences for the instabilities of the massive vector field
In this paper we have shown that the Lunin-Frolov-Krtous-Kubizn ́ak (LFKK) ansatz can be used to separate the Proca equations in the Kerr-Sen black hole background of the low energy heterotic string theory

Summary

Introduction

Dark matter candidates, e.g. [9]. For example, in the LIGO/LISA era ultralight bosons and superradiance can leave signatures in the signals of detected gravitational waves [8, 19,20,21]; see [12] for the most recent fully relativistic calculation of the gravitational wave signals. The LFKK ansatz has been applied to study the Proca equations in the background of the Chong-Cvetic-Lu-Pope black hole of D = 5 minimal gauged supergravity [42] where, as for Kerr-Sen, the principal tensor must be generalized to the case with torsion and is a weaker construction [43, 44]. In this case, the torsion is naturally identified with the Maxwell 3-form present in the spacetime, and both the principal tensor and the Proca equations pick up a corresponding torsion modification. The LFKK ansatz still applies and the (torsion) modified Proca equations decouple and separate [45]

Objectives

Discussion

Conclusion