Binary neutron-star mergers: a review of Einstein's richest laboratory

TL;DR

This review summarizes recent advances in understanding binary neutron-star mergers, emphasizing general-relativistic simulations, post-merger phenomena, and their astrophysical signatures, highlighting their importance as natural laboratories for Einstein's theories.

Contribution

It provides a comprehensive overview of the latest modeling techniques, simulation results, and astrophysical implications of neutron-star mergers, integrating diverse physical processes.

Findings

Progress in fully general-relativistic dynamical simulations

Insights into post-merger black-hole formation and accretion

Understanding of ejected material and nucleosynthesis processes

Abstract

The merger of binary neutron-stars systems combines in a single process: extreme gravity, copious emission of gravitational waves, complex microphysics, and electromagnetic processes that can lead to astrophysical signatures observable at the largest redshifts. We review here the recent progress in understanding what could be considered Einstein's richest laboratory, highlighting in particular the numerous significant advances of the last decade. Although special attention is paid to the status of models, techniques, and results for fully general-relativistic dynamical simulations, a review is also offered on initial data and advanced simulations with approximate treatments of gravity. Finally, we review the considerable amount of work carried out on the post-merger phase, including: black-hole formation, torus accretion onto the merged compact object, connection with gamma-ray burst engines, ejected material, and its nucleosynthesis.