Neutron Star Merger

GW170817 — gravitational waves, gamma-ray burst, and r-process nucleosynthesis in a kilonova

Phase: Inspiral Merger GRB Jet Kilonova Black Hole
GW170817 (2017-08-17): LIGO/Virgo detected two neutron stars (~1.37+1.37 M☉) spiraling together. In ~100 seconds before merger, gravitational wave frequency swept through the audio band. The merger produced: a short gamma-ray burst (GRB 170817A, 1.7 s delay), a kilonova (AT2017gfo) glowing from r-process heavy elements (gold, platinum, uranium), and likely a black hole. This single event confirmed neutron stars make heavy elements and measured H₀ independently.