Sharpening the dark matter signature in gravitational waveforms I: Accretion and eccentricity evolution

TL;DR

This paper refines the modeling of dark matter effects on gravitational wave signals from black hole binaries by including accretion and eccentricity evolution, showing significant dephasing and faster circularization.

Contribution

It introduces a comprehensive calculation of dark matter influence on binary evolution, incorporating accretion and eccentricity, validated by N-body simulations, advancing previous quasi-circular models.

Findings

Accretion causes significant waveform dephasing.

Dark matter spikes accelerate orbit circularization.

Models are validated with dedicated N-body simulations.

Abstract

Dark matter overdensities around black holes can alter the dynamical evolution of a companion object orbiting around it, and cause a dephasing of the gravitational waveform. Here, we present a refined calculation of the co-evolution of the binary and the dark matter distribution, taking into account the accretion of dark matter particles on the companion black hole, and generalizing previous quasi-circular calculations to the general case of eccentric orbits. These calculations are validated by dedicated N-body simulations. We show that accretion can lead to a large dephasing, and therefore cannot be neglected in general. We also demonstrate that dark matter spikes tend to circularize eccentric orbits faster than previously thought.