Probing wave-optics effects and low-mass dark matter halos with lensing of gravitational waves from massive black holes

Understand

The Laser Interferometer Space Antenna (LISA) will detect gravitational waves (GWs) emitted by massive black hole binaries (MBHBs) in the low-frequency ($\sim$mHz) band.

• Low-mass lenses, such as low-mass dark matter halos or subhalos, have sizes comparable to the wavelength of these GWs.
• Encounters with these lenses produce wave-optics (WO) effects that alter waveform phase and amplitude.
• Thus, a single event with observable WO effects can be used to probe the lens properties.