Distinguishing dark matter halos with Extreme mass ratio inspirals

Abstract

Using the static, spherically symmetric metric for a black hole (BH) immersed in dark matter (DM) halo characterized by Hernquist, Burkert, and Navarro-Frenk-White (NFW) density distributions, we calculate the orbital periods and precessions, along with the evolution of the semi-latus rectum and eccentricity for extreme mass ratio inspirals (EMRIs) surrounded by DM halos. For the Hernquist model, we find that the gravitational force exerted by the central BH is decreased by DM halos, while DM halos put additional gravitational force on the SCO. The presence of both Burkert-type and NFW-type DM halos enhances the gravitational force acting on the SCO, resulting in a decrease in the period $P$, with the decrease depending on $M/a_0^2$; additionally, we find that the reduction in orbital precession due to DM halos is influenced by $M/a_0^2$. The presence of DM halos leads to a slower evolution of EMRIs within Hernquist-type halos, while it accelerates evolution for EMRIs in Burkert-type and NFW-type halos; furthermore, it slows the decrease of eccentricity across all three types of DM halos. By calculating the number of orbital cycles and the gravitational waveform mismatches among these three types of DM halos, as well as between scenarios with and without DM halos, we find that DM halos can be detected when $M/a_0>10^{-5}$, $M/a_0>10^{-3}$, and $M/a_0>10^{-3}$ for Hernquist-type, NFW-type, and Burkert-type DM halos, respectively. Additionally, we can distinguish between NFW-type and Burkert-type DM halos when $M/a_0> 10^{-3}$; NFW-type and Hernquist-type DM halos, as well as Burkert-type and Hernquist-type DM halos, can be distinguished when $M/a_0> 10^{-5}$.