Inspirals into a charged black hole

TL;DR

This paper models the inspiral of a compact object into a charged black hole, analyzing electromagnetic and gravitational radiation effects, and finds that charge significantly influences inspiral dynamics and gravitational wave signals.

Contribution

It introduces a detailed model of charged black hole inspirals using Reissner-Nordström spacetime and quantifies the impact of charge on inspiral evolution and gravitational wave observations.

Findings

Charged black holes cause faster inspirals than neutral ones.

Electric charge affects gravitational wave signals when exceeding a specific threshold.

Charge influences the rate of energy dissipation during inspiral.

Abstract

We model the quasicircular inspiral of a compact object into a more massive charged black hole. Extreme and intermediate mass-ratio inspirals are considered through a small mass-ratio approximation. Reissner-Nordstr$\ddot{\text{o}}$m spacetime is used to describe the charged black hole. The effect of radiation reaction on the smaller body is quantified through calculation of electromagnetic and gravitational energy fluxes via solution of Einstein's and Maxwell's equations. Inspiral trajectories are determined by matching the orbital energy decay rate to the rate of radiative energy dissipation. We observe that inspirals into a charged black hole evolve more rapidly than comparable inspirals into a neutral black hole. Through analysis of a variety of inspiral configurations, we conclude that electric charge is an important effect concerning gravitational wave observations when the charge exceeds the threshold $|Q|/M \gtrsim 0.071 \sqrt{\epsilon}$, where $\epsilon$ is the mass ratio.