Prospects for detecting asteroid-mass primordial black holes in extreme mass-ratio inspirals with continuous gravitational waves

TL;DR

This paper explores the potential of future gravitational wave detectors to identify asteroid-mass primordial black holes as dark matter candidates through continuous gravitational wave signals from extreme mass-ratio inspirals.

Contribution

It demonstrates that advanced GW detectors could detect or constrain asteroid-mass PBHs as dark matter, highlighting the importance of improved data analysis techniques.

Findings

Future GW detectors can detect asteroid-mass PBHs in inspirals.

Enhanced data analysis methods improve current detection sensitivity.

Constraints could show asteroid-mass PBHs constitute less than all dark matter.

Abstract

Despite decades of research, the existence of asteroid-mass primordial black holes (PBHs) remains almost completely unconstrained and thus could still comprise the totality of dark matter (DM). In this paper, we show that standard searches for continuous gravitational waves -- long-lived, quasi-monochromatic signals -- could detect extreme mass-ratio inspirals of asteroid-mass PBHs in orbit around a stellar-mass companion using future gravitational-wave (GW) data from Einstein Telescope (ET) and the Neutron Star Extreme Matter Observatory (NEMO). We evaluate the robustness of our projected constraints against the eccentricity of the binary, the choice of the mass of the primary object, and the GW frequency range that we analyze. Furthermore, to determine whether there could be ways to detect asteroid-mass PBHs using current GW data, we quantify the impact of changes in current techniques on the sensitivity towards asteroid-mass PBHs. We show that methods that allow for signals with increased and more complicated frequency drifts over time could obtain much more stringent constraints now than those derived from standard techniques, though at slightly larger computational cost, potentially constraining the fraction of DM that certain asteroid-mass PBHs could compose to be less than one with current detectors.