Positrons and 511 keV Radiation as Tracers of Recent Binary Neutron Star Mergers

George M. Fuller, Alexander Kusenko, David Radice, and Volodymyr Takhistov
Phys. Rev. Lett. 122, 121101 – Published 29 March 2019
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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 ultrafaint dwarf galaxy Reticulum II, consistent with a rare NS-NS merger event, provides a smoking-gun signature of our proposal.

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  • Received 13 December 2018
  • Revised 8 February 2019

DOI:https://doi.org/10.1103/PhysRevLett.122.121101

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

George M. Fuller1,*, Alexander Kusenko2,3,†, David Radice4,5,‡, and Volodymyr Takhistov2,§

  • 1Department of Physics, University of California, San Diego La Jolla, California 92093-0354, USA
  • 2Department of Physics and Astronomy, University of California, Los Angeles Los Angeles, California 90095-1547, USA
  • 3Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
  • 4Institute for Advanced Study, Princeton, New Jersey 08540, USA
  • 5Department of Astrophysical Sciences, Princeton University Princeton, New Jersey 08544, USA

  • *gfuller@ucsd.edu
  • kusenko@ucla.edu
  • dradice@ias.edu
  • §vtakhist@physics.ucla.edu

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Issue

Vol. 122, Iss. 12 — 29 March 2019

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