On the Origin of Variable 511 keV Line Emission from the Galactic Center Region
Abstract
Variable narrow-line emission at 511 keV, due to positron annihilation, has been observed from the region of the Galactic center for over a decade with high-resolution Ge spectrometers. The variable nature of this emission suggests that a significant fraction of the observed radiation is produced by a single source in the central region of the Galaxy. Recent observations with an imaging gamma-ray spectrometer of low energy resolution have revealed a daylong burst of annihilation radiation from the X-ray source 1E 1740.7-2042 located at an angular distance of 0.9 deg from the Galactic center and aligned with a dense molecular cloud. It is proposed that the variable narrow 511 keV line emission is due to positrons released impulsively (time scale of about 1 day) from 1E 1740.7-2942 into the molecular cloud where they slow down and annihilate on a longer time scale of up to a year.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1992
- DOI:
- 10.1086/186426
- Bibcode:
- 1992ApJ...392L..63R
- Keywords:
-
- Black Holes (Astronomy);
- Galactic Nuclei;
- Positron Annihilation;
- Spectral Line Width;
- X Ray Sources;
- Emission Spectra;
- Energy Spectra;
- Gamma Ray Spectrometers;
- Molecular Clouds;
- Space Radiation;
- BLACK HOLE PHYSICS;
- GALAXY: CENTER;
- GAMMA RAYS: OBSERVATIONS;
- GAMMA RAYS: THEORY