Bremsstrahlung component of the diffuse galactic gamma-ray emission at MeV energies

Journal Article · Sun Apr 15 04:00:00 EST 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161952· OSTI ID:6862509

Sacher, W; Schoenfelder, V

Recently the galactic plane has been resolved at low and medium ..gamma..-ray energies in the directions toward the center and anticenter. Spectral measurements are now available at those energies, where the contribution of ..pi../sup 0/-decay from nuclear reactions of cosmic-ray protons (and heavier nuclei) with interstellar matter can be neglected. Under the assumption that most of the observed ..gamma..-ray flux below 30 MeV is produced by electron bremsstrahlung, restrictions on the energy spectrum of cosmic-ray electrons in interstellar space below 100 MeV are derived. The most accurate bremsstrahlung production cross sections of Koch and Motz and of Blumental and Gould are used in order to derive the bremsstrahlung production spectrum in interstellar space down to 10 keV-photon energies. If the low-energy ..gamma..-ray emission, as seen by most observers, is indeed produced by electron bremsstrahlung, then a high interstellar electron flux at MeV energy results, which-at higher energies-connects to the upper limit derived by Cummings, Stone, and Vogt. Such a high low-energy electron flux would be able to explain the ionization rate of 1 x 10/sup -15/ ion pairs (H-atom/sup -1/ s/sup -1/) in H I regions. Because of uncertainties in the low-energy ..gamma..-ray measurements, however, no definite conclusion is possible yet.

• Research Organization: Max-Planck-Institut fuer Physik and Astrophysik, Institut fuer extraterrestrische Physik
• OSTI ID: 6862509
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 279:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
COLLISIONS
COSMIC ELECTRONS
COSMIC GAMMA SOURCES
COSMIC PHOTONS
COSMIC RADIATION
COSMIC RAY SOURCES
CROSS SECTIONS
ELECTROMAGNETIC RADIATION
ELECTRON COLLISIONS
ELECTRON SPECTRA
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
FERMIONS
GALAXIES
IONIZING RADIATIONS
LEPTONS
MASSLESS PARTICLES
MILKY WAY
PHOTONS
RADIATIONS
SPECTRA