Multi-messenger Observations of a Binary Neutron Star Merger

Abstract

On 2017 August 17, the binary neutron star merger GW170817 was observed via gravitational waves by Advanced LIGO and Advanced Virgo, and ≈1.7 s later a short gamma‑ray burst (GRB 170817A) was detected. A global electromagnetic follow‑up found a kilonova (AT 2017gfo) in NGC 4993 within ≈11 hours, evolving from blue to red over ~10 days, with subsequent X‑ray and radio detections at ≈9 and ≈16 days post‑merger. This event marked the first-ever simultaneous detection across gravitational and electromagnetic spectra, inaugurating the era of multi‑messenger astrophysics.,