Gravitational waves from regular black holes in extreme mass-ratio inspirals

Abstract

We analyze a rotating regular black hole spacetime with an asymptotically Minkowski core, focusing on extreme mass-ratio inspiral (EMRIs) where a stellar-mass object inspirals a supermassive black hole under consideration. Such spacetimes are also called Kerr-like spacetimes, which motivate the investigation of black holes beyond general relativity and the test of the no-hair theorem. In the present article, we consider the eccentric equatorial motion of an inspiralling object in the background of a rotating regular black hole. The dynamics generate gravitational waves (GWs) that imply a loss in energy and angular momentum of the orbiting body. In this scenario, as a result of the radiation reaction, we analytically compute the orbital evolution of the moving object. Further, we generate the gravitational waveforms and constrain the non-Kerr parameter through dephasing and mismatch computations using Laser Interferometer Space Antenna (LISA) observations. Our result indicates that LISA can distinguish the effect of the additional non-Kerr/deviation parameter with the parameter as small as $\sim10^{-6}$. The constraint on the parameter in the regular black hole using the Fisher information matrix (FIM) can be obtained within a fraction error of $10^{-5}$. The estimates of our analysis with EMRIs present the possible detectability of Kerr-like geometries with future space-based detectors, and further open up ways to put a stringent constraint on non-Kerr parameters with more advanced frameworks.