Merger estimates for Kerr-Sen black holes

Abstract

The advent of gravitational wave observation starts a new era of precision tests of gravitational theory. Estimations of black holes mergers should come from any well established gravitational theories, provided that the theory has not been ruled out by observations. In this paper we consider the low energy limit of heterotic string theory where the associated rotating and charged black holes are described by the Kerr-Sen solution. We investigate the approximate final spins and quasinormal modes of the black hole resulting from the merger process. * haryanto.siahaan@unpar.ac.id

Absorption by stringy black holes

“…The difference between the two cases increases as the black holes approach the extremality, albeit being very small. A small difference between physical quantities associated to KN and KS black holes with the same normalized charge is also manifest in the case of their shadows [13,17,20,45].…”

“…In the low-energy limit of this model of gravity, there exists a charged rotating black hole solution, namely the Kerr-Sen (KS) black hole [11], which has been attracting a lot of attention. Several studies on the features of KS black holes were made, including shadow [12,13], Hawking radiation [14], absorption of charged particles and clouds [15,16], hidden symmetries [17], cosmic censorship [18,19] and merger estimates [20].…”

Kerr–Sen–Taub–NUT spacetime and circular geodesics

“…Furthermore, to ensure that there is no acceleration in r or x direction, the following constraints dV r,eff dr = 0, (4.11) and dV x,eff dx = 0, (4.12) must be fulfilled as well. The last equation is normally satisfied in most spacetimes without NUT parameter, for example those in Einstein-Maxwell-dilaton [41] and low energy limit of heterotic string [42] theories. However, when NUT parameter exists, Eq.…”

Rotating and charged Taub-NUT-(A)dS spacetimes on a 3-brane

“…It may give us predictions on reasonable orbit for some astrophysical objects or even light ring radius. Moreover, recently studies on these geodesics may provide us some estimates on black hole mergers [61,60]. Particularly for circular geodesics, one can employ the approach by writing down the corresponding radial effective potential directly from the metric as performed in [60,61], or alternatively from the associated Hamilton-Jacobi equation for a test particle.…”