Galactic plane gamma radiation

Abstract

Analysis of the complete data from SAS-2 accentuates the fact that the distribution of galactic gamma radiation has several similarities to that of other large-scale tracers of galactic structure. The gamma radiation shows no statistically significant variation with direction, and the spectrum seen along the plane is the same as that derived for the galactic component of the gamma radiation at high latitude. This uniformity of the energy spectrum, the smooth decrease in intensity as a function of galactic latitude, and the absence of any galactic gamma ray sources at high latitudes argue in favor of a diffuse origin for most of the galactic gamma radiation, rather than a collection of localized sources. All the localized sources identified in the SAS 2 data are associated with known compact objects on the basis of observed periodicities, except gamma195+5 Excluding those SAS 2 sources observed by COS-B and two other excesses (CG 312-1 and CG333+0) visible in the SAS 2 data associated with tangential directions of spiral arms, thera are eight remaining new sources in the COS-B catalog.