Hunting for the host galaxy groups of binary black holes and the
  application in constraining Hubble constant
  The discovery of gravitational-wave (GW) signals, produced by the coalescence
of stellar-mass binary black holes (SBBHs), opens a new window to study the
astrophysical origins and dynamical evolutions of compact binaries. In
addition, these GW events can be treated as the standard sirens to constrain
various cosmological parameters. Both issues require the host identification
for these GW events, with help of the spatial resolution of GW detector
networks. In this paper, we investigate the capabilities of various detector
networks for identifying the SBBHs' host galaxy groups, rather than their host
galaxies, which can overcome the influence of galaxies' proper motions in dark
matter halos for measuring the cosmological parameters. In our analysis, the
group catalog of SDSS DR7 with redshift $z\in(0.01,0.1)$ is considered as an
example of the application. We find that for the second-generation (2G)
detector network, the host galaxy groups of around $(0.7-6.9)$ SBBHs can be
identified per year assuming all sources are $30-30\ M_{\odot}$ binaries, and
that all five detectors in the network are in lock 100\% of the time. For the
3G detector network, this number becomes $(3.9-40.0)$ yr$^{-1}$. We also
investigate the potential constraint on the Hubble constant $H_0$ by these GW
events, if their redshift information is extracted from the candidates of host
galaxy groups. We find that, by five-year's full time observations, 2G detector
network is expected to give a constraint of $\Delta H_0/H_0\sim (1\%,4\%)$,
which can be more than two order smaller if considering the 3G detector
network.
