Galaxy lens reconstruction based on strongly lensed gravitational waves: similarity transformation degeneracy and mass-sheet degeneracy

Understand

Gravitational wave (GW) galaxy lens reconstruction is a crucial step for many GW lensing science applications.

• However, dark siren GW lensing (i.e.
• lensed GW without observed electromagnetic (EM) counterpart) suffers from similarity transformation degeneracy and mass-sheet degeneracy.
• We review these two degeneracies and discuss their implications on GW-based lens reconstruction and two well-known GW lensing science cases: the Hubble constant measurement and test for modified GW propagation.