Lensing of gravitational waves as a probe of compact dark matter

We study gravitational lensing of gravitational waves from compact object binaries as a probe of compact dark matter (DM) objects such as primordial black holes. Assuming a point mass lens, we perform parameter estimation of lensed gravitational wave signals from compact object binaries to determine the detectability of the lens with ground based laser interferometers. Then, considering binary populations that LIGO-Virgo has been probing, we derive a constraint on the abundance of compact DM from non-observation of lensed events. We find that the LIGO-Virgo observations imply that compact objects heavier than M-l = 200 M-circle dot cannot constitute all DM and less than 40 per cent of DM can be in compact objects heavier than M-l = 400 M-circle dot. We also show that the DM fraction in compact objects can be probed by LIGO in its final sensitivity for M-l > 40 M-circle dot reaching 2 per cent of the DM abundance at M-l > 200 M-circle dot, and by ET for M-l > 1 M-circle dot reaching DM fraction as low as 7 x 10(-5) at M-l > 40 M-circle dot.

Automated summary

The study focuses on gravitational lensing of gravitational waves from compact object binaries as a probe of compact dark matter (DM) objects such as primordial black holes. Through parameter estimation and analysis of binary populations, it is found that compact objects heavier than 200 solar masses cannot constitute all DM and those heavier than 400 solar masses can only account for less than 40% of DM. Additionally, it is shown that the fraction of DM in compact objects can be probed effectively by LIGO and ET reaching different DM abundance levels depending on the mass of the compact objects.