A fast radio burst in a globular cluster: why is this neutron star different from (almost) all other neutron stars?

Abstract

ABSTRACT Most fast radio burst (FRB) models are built from comparatively common astronomical objects: neutron stars, black holes, and supernova remnants. Yet FRB sources are rare, and most of these objects, found in the Galaxy, do not make FRB. Special and rare circumstances may be required for these common objects to be sources of FRB. The recent discovery of a repeating FRB in a globular cluster belonging to the galaxy M81 suggests a model involving a neutron star and a close binary companion, likely a white dwarf; both neutron stars and close binaries are superabundant in globular clusters. Magnetic interaction is a plausible, though unproven, mechanism of acceleration of relativistic particles that may radiate coherently as FRB. In such a model, the energy source is the orbital kinetic energy, and not limited by the magnetostatic energy of a neutron star. Double neutron star binaries cannot be the observed long-lived repeating FRB sources, but might make much shorter lived sources, and perhaps non-repeating FRB.