Speaker
Koutarou Kyotoku
Description
We propose that stellar-mass binary black holes like
GW150914 will become a tool to explore the
local Universe within ~100Mpc in the era of the Laser
Interferometer Space Antenna (LISA). High
calibration accuracy and annual motion of LISA could enable
us to localize up to ~60 binaries more
accurately than the error volume of ~100Mpc^3 without
electromagnetic counterparts under
moderately optimistic assumptions. This accuracy will give
us a fair chance to determine the host
object solely by gravitational waves. By combining the
luminosity distance extracted from
gravitational waves with the cosmological redshift
determined from the host, the local value of the
Hubble parameter will be determined up to a few % without
relying on the empirically constructed
distance ladder. Gravitational-wave cosmography would pave
the way for resolution of the disputed
Hubble tension, where the local and global measurements
disagree in the value of the Hubble
parameter at 3.4sigma level, which amounts to ~9%.
