The X-ray counterpart to the gravitational wave event GW 170817

Understand

A long-standing paradigm in astrophysics is that collisions- or mergers- of two neutron stars (NSs) form highly relativistic and collimated outflows (jets) powering gamma-ray bursts (GRBs) of short (< 2 s) duration.

• However, the observational support for this model is only indirect.
• A hitherto outstanding prediction is that gravitational wave (GW) events from such mergers should be associated with GRBs, and that a majority of these GRBs should be off-axis, that is, they should point away from the Earth.
• Here we report the discovery of the X-ray counterpart associated with the GW event GW170817.