Probing compact dark matter with gravitational wave fringes detected by the Einstein Telescope

Understand

Unlike the electromagnetic radiation from astrophysical objects, gravitational waves (GWs) from binary star mergers have much longer wavelengths and are coherent.

• For ground-based GW detectors, when the lens object between the source and the earth has mass $\sim 1-10^5M_\odot$, the diffraction effect should be considered since the chirping wavelengths are comparable to the scale of the barrier (its Schwarzschild radius).
• The waveform will thus be distorted as the fringes.
• In this work, we show that signals from the third-generation GW detectors like the Einstein Telescope (ET) would be a smoking gun for probing the nature of compact dark matter (CDM) or primordial black holes.