Probing the Universe’s expansion with multi-messenger astronomy

Thanks to the synergies between gravitational wave (GW) experiments, such as LIGO/Virgo/KAGRA, and electromagnetic observations of transients and galaxies, a variety of novel cosmological measurements has recently become possible. Several of these measurements rely on the use of GW events as “standard sirens”. Following the detection of the first electromagnetic counterpart to a GW event, GW170817, the first “bright” standard siren measurement has been performed. We will continue searching for optical counterparts to enable more bright siren analyses with the Gravitational Wave Multi-Messenger Astronomy DECam Survey (GW-MMADS), which I will briefly introduce. Standard siren measurements for “dark” events, i.e. without an electromagnetic counterpart, have also been performed, using cross-correlations with galaxy catalogs. In this talk I will present our latest bright and dark standard siren measurements, and also provide forecasts for multi-messenger cosmology in the upcoming years.