Gravitational-wave event rates as a new probe for dark matter microphysics

TL;DR

Gravitational-wave event rates can serve as a novel observational probe to distinguish different dark matter microphysics models by analyzing their impact on cosmic structure formation and black hole merger rates.

Contribution

This paper demonstrates that gravitational-wave observations can reveal dark matter microphysical properties by linking merger rates to small-scale structure suppression effects.

Findings

Suppression of small-scale structure reduces high-redshift black hole merger rates.

Future gravitational-wave data can differentiate dark matter scenarios beyond the standard model.

Merger rate variations are sensitive to dark matter properties like warm or fuzzy dark matter.

Abstract

We show that gravitational waves have the potential to unravel the microphysical properties of dark matter due to the dependence of the binary black hole merger rate on cosmic structure formation, which is itself highly dependent on the dark matter scenario. In particular, we demonstrate that suppression of small-scale structure -- such as that caused by interacting, warm, or fuzzy dark matter -- leads to a significant reduction in the rate of binary black hole mergers at redshifts $z\gtrsim5$. This shows that future gravitational-wave observations will provide a new probe of physics beyond the $\Lambda$CDM model.