Gravitational waves with dark matter minispikes: the combined effect

TL;DR

This paper studies how dark matter minispikes around intermediate-mass black holes influence gravitational wave signals from inspirals, highlighting the significance of accretion effects on waveform phase shifts detectable by future observatories.

Contribution

It provides a comprehensive analysis of the combined effects of gravitational pull, dynamical friction, and accretion on gravitational waveforms in systems with dark matter minispikes, emphasizing the importance of accretion in GW detection.

Findings

Merger time is significantly reduced for smaller IMBHs with dense DM minispikes.

Accretion effects are small in mass but cause detectable phase shifts in GW signals.

Phase shifts due to accretion are large enough to be observed by LISA, Taiji, and Tianqin.

Abstract

It was shown that the dark matter(DM) minihalo around an intermediate mass black hole(IMBH) can be redistributed into a cusp, called the DM minispike. We consider an intermediate-mass-ratio inspiral consisting of an IMBH harbored in a DM minispike with nonannihilating DM particles and a small black hole(BH) orbiting around it. We investigate gravitational waves(GWs) produced by this system and analyze the waveforms with the comprehensive consideration of gravitational pull, dynamical friction and accretion of the minispike and calculate the time difference and phase difference caused by it. We find that for a certain range of frequency, the inspiralling time of the system is dramatically reduced for smaller central IMBH and large density of DM. For the central IMBH with $10^5M_\odot$, the time of merger is ahead, which can be distinguished by LISA, Taiji and Tianqin. We focus on the effect of accretion and compare it with that of gravitational pull and friction. We find that the accretion mass is a small quantity compared to the initial mass of the small BH and the accretion effect is inconspicuous compared with friction. However, the accumulated phase shift caused by accretion is large enough to be detected by LISA, Taiji and Tianqin, which indicate that the accretion effect can not be ignored in the detection of GWs.