Next-generation dark sirens for precision measurement of the Hubble Constant
Gravitational waves (GW) from merging compact objects provide a new way to measure the expansion rate of the Universe through “standard sirens.” While the current best result relied on events with electromagnetic counterparts, most detections, especially binary black hole mergers, are “dark” and lack such signals. Even so, these dark sirens can be used for cosmology by statistically linking them to galaxies in large surveys (i.e. the galaxy-catalog method).
In this talk, we show how golden and silver dark sirens can lead to meaningful measurements of the Hubble constant. Using data from the Hobby–Eberly Telescope Dark Energy Experiment, we demonstrate that dedicated spectroscopic follow-up surveys provide the necessary redshift information with high completeness and precision. With upcoming improvements in GW detectors, this approach could yield a measurement of the Hubble constant at the few-percent level within the next few years. Standard sirens thus offer a powerful and independent way to address the current tension in measurements of the expansion rate of the Universe.