A Standard Siren Measurement of the Hubble Constant from GW170817 without the Electromagnetic Counterpart
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 redshifts from all of the galaxies with the distance estimate from GW170817 provides an estimate of the Hubble constant, H_0. Considering all galaxies brighter than 0.626L*_B as equally likely to host a binary neutron star merger, we find H_0 – 77^(+37)_(-18) km s^(−1) Mpc^(−1) (maximum a posteriori and 68.3% highest density posterior interval; assuming a flat H_0 prior in the range [10, 220] km s^(−1) Mpc^(−1)). We explore the dependence of our results on the thresholds by which galaxies are included in our sample, and we show that weighting the host galaxies by stellar mass or star formation rate provides entirely consistent results with potentially tighter constraints. By applying the method to simulated gravitational-wave events and a realistic galaxy catalog we show that, because of the small localization volume, this statistical standard siren analysis of GW170817 provides an unusually informative (top 10%) constraint. Under optimistic assumptions for galaxy completeness and redshift uncertainty, we find that dark binary neutron star measurements of H_0 will converge as 40%/√(N), where N is the number of sources. While these statistical estimates are inferior to the value from the counterpart standard siren measurement utilizing NGC 4993 as the unique host, H_0 = 76^(+19)_(-13) km s^(−1) Mpc^(−1) (determined from the same publicly available data), our analysis is a proof-of-principle demonstration of the statistical approach first proposed by Bernard Schutz over 30 yr ago.
© 2019 The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal itation and DOI. Received 2018 October 17; revised 2018 December 16; accepted 2018 December 17; published 2019 January 22. We thank Chihway Chang, Alison Coil, and Risa Wechsler for valuable discussions about galaxy properties. M.F. was supported by the NSF Graduate Research Fellowship Program under grant DGE-1746045. M.F. and D.E.H. were supported by NSF grant PHY-1708081. They were also supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF grant PHY-1125897 and an endowment from the Kavli Foundation. D.E.H. also gratefully acknowledges support from a Marion and Stuart Rice Award. The authors acknowledge the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), and the Foundation for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific Research, for the construction and operation of the Virgo detector and the creation and support of the EGO consortium. We are grateful to the LIGO and Virgo collaborations for releasing sky map data for GW170817 at dcc.ligo.org/LIGO-P1800061/public. This work has made use of CosmoHub. CosmoHub has been developed by the Port d'Informació Cientfica (PIC), maintained through a collaboration of the Institut de Fsica d'Altes Energies (IFAE) and the Centro de Investigaciones Energticas, Medioambientales y Tecnológicas (CIEMAT), and was partially funded by the "Plan Estatal de Investigación Cientfica y Tcnica y de Innovación" program of the Spanish government. We also acknowledge the First Two Years data release (https://www.ligo.org/scientists/first2years/).
Submitted - 1807.05667.pdf
Published - Fishbach_2019_ApJL_871_L13.pdf