Intermediate-mass-ratio inspirals with general dynamical friction in dark matter minispikes

TL;DR

This paper investigates how dynamical friction from dark matter minispikes influences the orbital eccentricity and gravitational wave signals of intermediate-mass-ratio inspirals, revealing potential methods to detect dark matter properties via GW observations.

Contribution

It introduces a comprehensive analysis of general dynamical friction effects on IMRIs, establishing a novel relation between GW strain peak frequency and dark matter minispike density profile.

Findings

Dynamical friction can increase orbital eccentricity for certain dark matter profiles.

The characteristic GW strain is suppressed at low frequencies and peaks shift with dark matter profile.

A new analytical relation links GW peak frequency to dark matter minispike parameters.

Abstract

The intermediate-mass-ratio inspirals (IMRIs) may be surrounded by dark matter (DM) minispikes. The dynamical friction from these DM minispike structures can affect the dynamics and the gravitational wave (GW) emission of the IMRIs. We analyze the effects of general dynamical friction, with a particular contribution from DM particles moving faster than the stellar-mass black hole in an eccentric IMRI. Our calculation show that these DM particles tends to eccentricify the orbit, therefore the evolution of the eccentricity depends on the competition between the fast moving DM particles and the slow moving DM particles. The results show that the dynamical friction enhances the eccentricity when $\gamma_\mathrm{sp}\lesssim2.0$, and the general dynamical friction is able to increase the eccentricity. We also analyze the effects of general dynamical friction on the GW characteristic strain. The results indicate that the characteristic strain is suppressed at lower frequencies, and the peak value of the characteristic strain occurs at higher frequencies as the power law index of DM minispike $\gamma_\mathrm{sp}$ increases. For the first time, a relation between the frequency peak value of characteristic strain of GWs and $\gamma_\mathrm{sp}$ is established. Using this analytical relation, the presence of DM and its halo density may be determined potentially from future GW data.