ESA Science & Technology - Global Galactic Distribution of the 1.275 MeV

Publication date: 15 November 2005

Authors: Iyudin, A., et al.

Journal: A&A
Volume: 443
Issue: 2
Page: 477-483
Year: 2005

Copyright: ESO 2005

We present results of the analysis of 1.275 MeV gamma-ray line global distribution derived from the all-sky data accumulated by COMPTEL on board the Compton Gamma Ray Observatory (CGRO) from 1991 to 1997. Previously the 1.275 MeV gamma-ray line was believed to be largely produced in the decay of radioactive isotope ²²Na that is synthesised in the classical nova (CN) thermonuclear runaway (TNR). Another way to produce the 1.275 MeV line emission is via the excitation of ²²Ne nuclei, e.g. through the low-energy cosmic ray interactions with the nuclei of the interstellar matter that lead to the production of ²²Ne*, or of ²²Na. This scenario, as we now believe, can be dominant in contributing to the total 1.275 MeV gamma-ray line emission from the galactic bulge.

Unfortunately, systematic uncertainties in the analysis of the COMPTEL data hinder a clear distinction between two alternative scenarios.