Diffuse 0. 511 MeV line emission and the distribution of positron annihilation in the galaxy

Journal Article · Tue Sep 01 04:00:00 EDT 1992 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/171772· OSTI ID:7178985

Skibo, J G; Ramaty, R; Leventhal, M ^[1]

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1. NASA, Goddard Space Flight Center, Greenbelt, MD (United States)

We model the distribution in the Galaxy of 0.511 MeV line emission and the implied positron annihilation using plausible distributions based on observations at other photon energies. We use 0.511 MeV line observations from the Galactic center and from directions away from the Galactic center to normalize the two-dimensional 0.511 MeV sky maps. We find that in order to understand all of the available data it is necessary to invoke the presence of a time-variable component of 0.511 MeV line emission in addition to an underlying diffuse component. The large 0.511 MeV fluxes observed with broad field of view detectors, such as the SMM gamma-ray spectrometer, can be reconciled with the small fluxes seen with narrow field-of-view instruments (GRIS and OSSE) from directions away from the Galactic center if the diffuse emission follows the distribution of Galactic novae for which the recently detected 0.511 MeV line emission from the Galactic center with OSSE is predominantly of diffuse origin. For future GRIS and HEXAGONE observations from the direction of the Galactic center we predict a minimum 0.511 MeV line flux of (6.0 +/- 0.9) x 10 exp -4 photons/sq cm/s. 32 refs.

• OSTI ID: 7178985
• Journal Information: Astrophysical Journal; (United States), Journal Name: Astrophysical Journal; (United States) Vol. 397:1; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

662100* -- General Theory of Particles & Fields-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ABUNDANCE
COSMIC RAY SPECTROMETERS
EMISSION SPECTRA
ENERGY RANGE
GALAXIES
GAMMA SPECTROMETERS
LEPTON REACTIONS
LUMINOSITY
MEASURING INSTRUMENTS
MEV RANGE
MEV RANGE 01-10
NUCLEAR REACTIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
POSITRON REACTIONS
SPECTRA
SPECTROMETERS