2017d), which resulted in six independent detections of AT2017gfo (Coulter etВ al. 2017), the theoretically predicted radioactively-powered kilonova, whose precise location enabled the identification of вЂњoff-axisвЂќ afterglow emission (Troja etВ al. 2017) that has been detected until more than two years later. These discoveries culminated in a suite of papers published only two months after the first detection, with contributions from thousands of astronomers and astrophysicists, ushering in the new era of GW multimessenger astrophysics.

For decades, the scientific promise of these sources has been known, and the first event certainly met expectations with, on average, more than three papers written per day over the first two years. There have been only three convincing multimessenger detections of individual astrophysical sources: neutrinos and photons from the core-collapse supernova SN 1987A (Hirata etВ al. 1987), gravitational waves and photons from a binary neutron star merger (this event Abbott etВ al. 2017d), and likely neutrinos and photons from a flaring blazar (Aartsen etВ al. The modern era of time domain, multimessenger astrophysics will hopefully result in multiple detections of multiple source classes with multiple messengers. Binary Neutron Star (BNS) and Neutron StarвЂ“Black Hole (NSBH) mergers, collectively referred to here as NS mergers, will be important astrophysical multimessenger sources for the foreseeable future.

Several papers and reviews on the astrophysics of NS mergers have been written, both before and after GW170817. Several papers have been written on science beyond astrophysics enabled by observations of these events. When available, we reference manuscripts that contain more detailed discussions.

Neutron star universe sandbox 2