A beta decay radiation signature from neutron-rich gamma-ray bursts?

Abstract

Core collapse of massive stars and binary neutron stars or black hole–neutron star binarymergers are likely progenitors of long and short duration gamma-ray bursts respectively.Neutronized material in the former and neutron star material in the latter are ejected bythe central engine implying a neutron-rich jet outflow. A free neutron, however, beta decaysto a proton, an electron (beta) and an anti-neutrino in about fifteen minutesin its rest frame. Sudden creation of a relativistic electron is accompanied byradiation with a unique temporal and spectral signature. We calculate here thisradiation signature collectively emitted by all beta decay electrons from neutron-richoutflow. Detection of this signature may thus provide strong evidence for notonly neutron but also for proton content in the relativistic gamma-ray burst jets.