2004/05/31 by Gianfranco Bertone, Alexander Kusenko, Sergio Palomares-Ruiz +3 · 44 citations
Physics and Astronomy · #Annihilation #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Bulge #Electron #Galactic Center #Galaxy #Gamma ray #Gamma-ray burst #Gamma-ray bursts and supernovae #Line (geometry) #Nuclear physics #Photon #Physics #Positron #astro-ph #hep-ph
paper · pdf · doi:10.1016/j.physletb.2006.03.022
published in Physics Letters B 636(1), 20-24 (Elsevier BV) · 12 pages; substantial changes; to appear in Phys. Lett. B
arxiv created 2006/03/10 · openalex publication_date 2006/03/21 · arxiv updated 2014/10/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A recent observation of the 511 keV electron-positron annihilation line from the Galactic bulge has prompted a debate on the origin of the galactic positrons responsible for this emission. Assuming equilibrium between annihilation and injection of positrons in the Galaxy, we investigate the possibility that positrons were produced by past gamma ray bursts (GRBs). We compare the positron annihilation rate inferred from the observed 511 keV line with the predicted injection rate due to electron-positron pairs leaking out of individual GRBs and those pairs produced by GRB photons in the dense molecular clouds at the Galactic center. We conclude that the proposed scenario is marginally consistent with observations, and can reproduce the observed normalization of the annihilation line only for higher-than-average values of the GRB rate in the Galaxy and/or the molecular clouds optical depth for pair production.