Adiabatic inspirals under electromagnetic radiation reaction on Kerr spacetime

A compact body in orbit about a black hole loses orbital energy and angular momentum through radiation-reaction processes, inspiralling toward the black hole until a final plunge. Here we consider a scenario with a charged compact body in which fluxes of electromagnetic radiation drive this inspiral. We calculate trajectories in the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo stretchy="false">(</a:mo><a:mi>p</a:mi><a:mo>,</a:mo><a:mi>e</a:mi><a:mo stretchy="false">)</a:mo></a:math> plane for inspirals in the equatorial plane of a rotating black hole within the adiabatic (orbital-averaged-dissipative) approximation. We make comparisons with a nonrelativistic Keplerian approximation based on the Abraham-Lorentz force law, and with standard gravitational-wave driven scenarios. We find that EM-driven inspirals are less efficiently circularized (i.e. orbits remain more eccentric at the point of plunge) than their gravitational counterparts, and we quantify the effect of black hole spin.