Amplitude modulation in binary gravitational lensing of gravitational waves

Understand

We investigate the detectability of gravitational waves (GWs) lensed by a system that consists of binary black holes as lenses using time-domain numerical simulations.

• The gravitational lensing potential of this system is no longer static but evolves with time.
• When GWs from the source pass through the binary lens, their amplitudes can be modulated, which is similar to the phenomenon of amplitude modulation (AM) in radio communication.
• We find that even the frequency of the binary lens itself is too low to be detected by the LISA detection band, the sidebands in the spectrum of the lensed GWs due to AM can still be within the sensitive range of the detection band.