Gamma-rays from atomic and molecular gas in the first galactic quadrant
Caraveo, P. A.; Bignami, G. F.; Strong, A. W.; Hermsen, W.; Montmerle, T.; Lebrun, F.; Bennett, K.; Buccheri, R.; Kanbach, G.; Mayer-Hasselwander, H. A.; Paul, J. A.; Wills, R. D.; Sacco, B.; Bloemen, J. B. G. M.; Gottwald, M.; Thaddeus, P.; Dame, T. M.; Cohen R. S.
France, Netherlands, Italy, Germany, United States, Spain
Abstract
The fully sampled Columbia 1 deg CO survey and the Berkeley H I survey are compared with the COS B gamma-ray survey. As a first step, the study is limited to the high-energy gamma-rays (E greater than 300 MeV). It is found that a simple model, in which uniformly distributed cosmic rays interact with the interstellar gas, as traced by H I and CO, can account for almost all the observed gamma-rays. Furthermore, if the contribution from point sources to the gamma-ray flux is significant, these sources must have a galactic distribution similar to that of CO. The analysis permits calibration of the ratio between H2 column density and integrated CO line intensity: N(H2)/W(CO) = (1-3) 10 to the 20th molecules per sq cm k km per s.