Positrons and 511 keV radiation as tracers of recent binary neutron star mergers
Abstract
Neutron-rich material ejected from neutron star-neutron star (NS-NS) and neutron star-black hole (NS-BH) binary mergers is heated by nuclear processes to temperatures of a few hundred keV, resulting in a population of electron-positron pairs. Some of the positrons escape from the outer layers of the ejecta. We show that the population of low-energy positrons produced by NS-NS and NS-BH mergers in the Milky Way can account for the observed 511-keV line from the Galactic center (GC). Moreover, we suggest how positrons and the associated 511-keV emission can be used as tracers of recent mergers. Recent discovery of 511 keV emission from the ultra-faint dwarf galaxy Reticulum II, consistent with a rare NS-NS merger event, provides a smoking-gun signature of our proposal.
Keywords
Cite
@article{arxiv.1811.00133,
title = {Positrons and 511 keV radiation as tracers of recent binary neutron star mergers},
author = {George M. Fuller and Alexander Kusenko and David Radice and Volodymyr Takhistov},
journal= {arXiv preprint arXiv:1811.00133},
year = {2019}
}
Comments
5 pages + 2 page supplement, 4 figures; v3: minor modifications, published version