Abstract
The current and next observation seasons will detect hundreds of
gravitational waves (GWs) from compact binary systems coalescence at
cosmological distances. When combined with independent electromagnetic
measurements, the source redshift will be known, and we will be able to obtain
precise measurements of the Hubble constant $H_0$ via the distance-redshift
relation. However, most observed mergers are not expected to have
electromagnetic counterparts, which prevents a direct redshift measurement. In
this scenario, one of the possibilities is to use the dark sirens method that
statistically marginalizes over all the potential host galaxies within the GW
location volume to provide a probabilistic redshift to the source. Here we
presented $H_{0}$ measurements using two new dark sirens compared to previous
analyses using DECam data, GW190924$\_$021846 and GW200202$\_$154313. The
photometric redshifts of the possible host galaxies of these two events are
acquired from the DECam Local Volume Exploration Survey (DELVE) carried out on
the Blanco telescope at Cerro Tololo in Chile. The combination of the $H_0$
posterior from GW190924$\_$021846 and GW200202$\_$154313 together with the
bright siren GW170817 leads to $H_{0} = 68.84^{+15.51}_{-7.74}\,
\rm{km/s/Mpc}$. Including these two dark sirens improves the 68% confidence
interval (CI) by 7% over GW170817 alone. This demonstrates that the inclusion
of well-localized dark sirens in such analysis improves the precision with
which cosmological measurements can be made. Using a sample containing 10
well-localized dark sirens observed during the third LIGO/Virgo observation
run, we determine a measurement of $H_{0} = 76.00^{+17.64}_{-13.45}\, \rm{km
/s/Mpc}$.