title: Stringent constraint on galactic positron production.
abstract: The intense 0.511 MeV gamma-ray line emission from the Galactic Center observed by INTEGRAL requires a large annihilation rate of nonrelativistic positrons. If these positrons are injected at even mildly relativistic energies, higher-energy gamma rays will also be produced. We calculate the gamma-ray spectrum due to inflight annihilation and compare it with the observed diffuse Galactic gamma-ray data. Even with a simplified but conservative treatment, we find that the positron injection energies must be less than or similar to 3 MeV, which strongly constrains models for Galactic positron production.
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Beacom
authors.forename: Hasan
authors.initials: H
authors.lastname: Yüksel