Measurement of Hubble constant with stellar-mass binary black holes
  The direct detections of gravitational waves (GW) from merging binary black
holes (BBH) by aLIGO have brought us a new opportunity to utilize BBH for a
measurement of the Hubble constant. In this paper, we point out that there
exists a small number of BBH that gives significantly small sky localization
volume so that a host galaxy is uniquely identified. Then a redshift of a BBH
is obtained from a spectroscopic follow-up observation of the host galaxy.
Using these redshift-identified BBH, we show that the Hubble constant is
measured at a level of precision better than 1% with advanced detectors like
aLIGO at design sensitivity. Since a GW observation is completely independent
of other astrophysical means, this qualitatively new probe will help resolve a
well-known value discrepancy problem on the Hubble constant from cosmological
measurements and local measurements.
