Eccentricity evolution of extreme-mass-ratio inspirals under Chandrasekhar dynamical friction

Abstract

Recent work has shown that the circularization of a binary due to gravitational wave emission can be counteracted by the eccentricity-increasing mechanism of dynamical friction. In this work, we examine the eccentricity evolution of an extreme-mass-ratio inspiral evolving under dynamical friction, considering the full Chandrasekhar formula in place of the power law limit. We show that the orbital eccentricities reached by the binary are lower in the exact treatment−as modulated by the velocity dispersion of the medium−relative to the power law approximation which overestimates the eccentricity increase of the binary.