Gravitational waves refine cosmic expansion rate ⚡ экспресс
A new measurement of the Hubble constant is presented, based on a joint analysis of standard sirens and three two-point correlation functions (3×2pt), which include weak gravitational lensing and galaxy clustering. Data from Dark Energy Survey Year 3 and the gravitational-wave transient catalog GWTC-4 from the LIGO-Virgo-KAGRA collaboration were used, along with measurements for event GW170817: the redshift of the host galaxy and the inclination angle of the superluminal jet. The result is H₀ = 67.9^{+4.4}_{-4.3} km/s/Mpc with 6.4% precision; the constraint on the matter abundance Ωm is improved by 22% compared to DES alone. Without jet information, the precision of H₀ drops to 9.9%. The work demonstrates that incorporating standard sirens into cosmological analysis of large surveys is a promising path toward resolving the Hubble tension.
Measuring the universe’s expansion is like timing a race when the track stretches. Neutron star mergers act as standard sirens: their gravitational waves ring out with a known “volume,” so fainter signals mean greater distance.
A new study paired the siren from merger GW170817 with a galaxy map tracing matter, including dark matter (invisible mass first detected by Vera Rubin). The result: the Hubble constant (named after Edwin Hubble) is 67.9 km/s per megaparsec—so a galaxy 3.26 million light-years away recedes at that speed—with just 6.4% uncertainty.
This value eases a cosmic dispute: the early universe’s afterglow suggests slower expansion, while nearby exploding stars point to faster. The new number falls between them, highlighting the strength of cross-checking methods. Remarkably, the spacetime ripples from GW170817 jiggled our detectors by less than a proton’s width, yet clocked the universe’s growth.
🎯 The term 'standard siren' echoes 'standard candle,' but while candles use light, sirens use gravitational waves—a clever twist on an old cosmic yardstick.