http://arxiv.org/abs/1807.05667
We perform a statistical standard siren analysis of GW170817. Our analysis does not utilize knowledge of NGC 4993 as the unique host galaxy of the optical counterpart to GW170817. Instead, we consider each galaxy within the GW170817 localization region as a potential host; combining the $H_0$ values from all the galaxies provides a final measurement of $H_0$. We explore the dependence of our results on the galaxy thresholds, as well as the impact of weighting the galaxies by stellar mass and star-formation rate. Considering all galaxies brighter than $0.01 L^\star_B$ (containing $\sim99\%$ of the total blue luminosity) as equally likely to host a BNS merger, we find $H_0= 76^{+48}{-23}$ km s$^{-1}$ Mpc$^{-1}$ (maximum a posteriori and 68.3% highest density posterior interval; all results are from publicly available LIGO/Virgo sky maps using approximations to the line-of-sight distance distributions). Restricting only to galaxies brighter than $0.626 L^\star_B$ (containing $\sim50\%$ of the total blue luminosity) tightens the measurement to $H_0= 77^{+37}{-18}$ km s$^{-1}$ Mpc$^{-1}$. We show that weighting the host galaxies by stellar mass or star-formation rate provides entirely consistent results with potentially tighter constraints. While these statistical estimates are inferior to the value from the counterpart standard siren measurement utilizing NGC 4993 as the unique host, our analysis is a proof-of-principle demonstration of the statistical approach first proposed by Bernard Schutz over 30 years ago. This method is of particular promise in the case of binary black holes, since they are not expected to have optical counterparts, and they occur at sufficient rates that the combined statistical standard siren measurements from many events may offer precision measurements of the luminosity distance-redshift relation to high ($z\lesssim1$) redshift.
M. Fishbach, R. Gray, I. Hernandez, et. al.
Tue, 17 Jul 18
3/79
Comments: 9 pages, 5 figures