Relativistic Events & Mergers

The inspiral and merger of two compact objects — black holes or neutron stars — radiating a chirp of gravitational waves. Since 2015 these have been heard routinely; neutron-star mergers also shine as kilonovae.

The most luminous electromagnetic events in the universe — brief, intense flashes of gamma rays. Long bursts come from the collapse of massive stars; short bursts from the mergers of neutron stars. Each is followed by a fading multi-wavelength afterglow.

The optical and infrared glow that follows the merger of two neutron stars, powered by the radioactive decay of the heavy elements forged in the merger. The 2017 event GW170817, seen in gravitational waves and light, was the landmark of multi-messenger astronomy.

Sudden, intense bursts of gamma and X-rays from magnetars — neutron stars with the strongest magnetic fields known. Their giant flares are so bright they can be detected across the galaxy, and are now linked to some fast radio bursts.