The synergy between gravitational wave experiments and large galaxy surveys such as the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) is most prominent in the standard siren method, which has already enabled several measurements of the Hubble Constant. A standard siren analysis was performed using GW170817 and its host galaxy for the first time, and we have later extended the analysis to compact object binary merger events (GW170814 and the recent GW190814) without a counterpart using a DES galaxy catalog. Interesting constraints on the Hubble Constant are expected to be placed with this method using data from the next LIGO/Virgo/KAGRA observing runs.
While galaxies' peculiar velocities represent one of the main sources of systematic uncertainty for standard siren measurements with nearby gravitational wave events, they also contain information about the growth of structure and gravity. In this talk, I will present prospects for measuring peculiar velocities using distances from gravitational wave events to infer cosmological parameters, and discuss how this probe will place competitive constraints on the growth index as a test for General Relativity.
Marc Manera, Pere Masjuan, Stefano Terzo