New Gravitational-Wave Method Measures Hubble Constant

Astrophysicists from the University of Illinois Urbana-Champaign and the University of Chicago have developed a new method, called the 'stochastic siren method,' to measure the Hubble constant using the gravitational-wave background. This innovative approach analyzes the combined signal from countless distant black hole mergers, which are too faint to be individually observed, to estimate the universe's expansion rate. The method aims to resolve the 'Hubble tension,' a significant discrepancy between measurements of the Hubble constant based on the early universe versus the more recent universe. The research, led by Nicolás Yunes and Daniel Holz, with Bryce Cousins as lead author, has been accepted for publication in Physical Review Letters. As gravitational wave detectors like those operated by the LIGO-Virgo-KAGRA Collaboration become more sensitive, this technique is expected to provide more precise measurements and potentially detect the gravitational-wave background within six years, offering new insights into the age and composition of the universe.