The deaths of ordinary stars herald the births of compact objects: white dwarfs, neutron stars, and black holes. THEA members are engaged in almost all aspects of the study of compact objects. Magnetized neutron stars - pulsars and magnetars - emit luminous radiation powered by their rotational and magnetic energy reservoirs, respectively. Despite decades of research, the mechanisms by which this energy is extracted from the neutron star interior and magnetosphere, and ultimately emitted as electromagnetic radiation from radio to gamma-rays, remains poorly understood (Beloborodov, Levin, Metzger, Sironi and Ruderman).
Transient flares from magnetars are strong contenders for the central engines of the recently discovered phenomena of fast radio bursts, as explored by THEA members (Beloborodov, Levin, Metzger, Sironi). The births of rapidly spinning magnetars and black holes in supernovae and neutron star mergers may be connected to phenomena as diverse as superluminous supernovae and gamma-ray bursts (Beloborodov, Metzger, Ruderman). White dwarfs and neutron stars also generate luminous transients from the sudden release of energy when nuclear fuel ignites on their surfaces, giving rise to X-ray bursts and novae, respectively (Levin, Metzger).