Strong lensing of gravitational waves as seen by LISA

Understand

We discuss strong gravitational lensing of gravitational waves from merging of massive black hole binaries in the context of the LISA mission.

• Detection of multiple events would provide invaluable information on competing theories of gravity, evolution and formation of structures and, with complementary observations, constraints on H_0 and other cosmological parameters.
• Most of the optical depth for lensing is provided by intervening massive galactic halos, for which wave optics effects are negligible.
• Probabilities to observe multiple events are sizable for a broad range of formation histories.