We present a measurement of the Hubble constant H0 using the gravitational wave (GW) event GW190814, which resulted from the coalescence of a 23 M black hole with a 2.6 M compact object, as a standard siren. No compelling electromagnetic counterpart has been identified for this event; thus our analysis accounts for thousands of potential host galaxies within a statistical framework. The redshift information is obtained from the photometric redshift (photo-z) catalog from the Dark Energy Survey. The luminosity distance is provided by the LIGO/Virgo gravitational wave sky map. Since this GW event has the second-smallest localization volume after GW170817, GW190814 is likely to provide the best constraint on cosmology from a single standard siren without identifying an electromagnetic counterpart. Our analysis uses photo-z probability distribution functions and corrects for photo-z biases. We also reanalyze the binary black hole GW170814 within this updated framework. We explore how our findings impact the H0 constraints from GW170817, the only GW merger associated with a unique host galaxy. From a combination of GW190814, GW170814, and GW170817, our analysis yields H72.0+12-8.2 km s-1, Mpc-1 0 8.2 12 1(68% highest-density interval, HDI) for a prior in H0 uniform between [20 and 140] km s-1 Mpc-1 . The addition of GW190814 and GW170814 to GW170817 improves the 68% HDI from GW170817 alone by ∼18%, showing how well-localized mergers without counterparts can provide a significant contribution to standard siren measurements, provided that a complete galaxy catalog is available at the location of the event.
Original languageEnglish
Article numberL33
Number of pages11
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 7 Sept 2020


  • cosmology
  • cosmological parameters
  • gravitational waves
  • Hubble constant
  • redshift surveys
  • surveys
  • graviational wave astronomy
  • UKRI
  • STFC

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