| Abstract: | We present a multi-messenger measurement of the Hubble constant H_0 using the
binary-black-hole merger GW170814 as a standard siren, combined with a
photometric redshift catalog from the Dark Energy Survey (DES). The luminosity
distance is obtained from the gravitational wave signal detected by the
LIGO/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information
is provided by the DES Year 3 data. Black-hole mergers such as GW170814 are
expected to lack bright electromagnetic emission to uniquely identify their
host galaxies and build an object-by-object Hubble diagram. However, they are
suitable for a statistical measurement, provided that a galaxy catalog of
adequate depth and redshift completion is available. Here we present the first
Hubble parameter measurement using a black-hole merger. Our analysis results in
$H_0 = 75.2^{+39.5}_{-32.4}~{
m km~s^{-1}~Mpc^{-1}}$, which is consistent with
both SN Ia and CMB measurements of the Hubble constant. The quoted 68% credible
region comprises 60% of the uniform prior range [20,140] ${
m
km~s^{-1}~Mpc^{-1}}$. This result shows that even a single dark siren can
provide a constraint on the Hubble constant, albeit a weak one. Future
combinations of many sirens will lead to improved constraints. A multifold
increase in the LVC event detection rate is expected in the coming years, and
this bodes well since future combinations of many additional sirens will lead
to improved constraints. |
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