The interrelation of cosmic -rays and interstellar gas in the range l:65-180

Abstract

New data on the distribution of molecular hydrogen in the first and second quadrants allow a detailed analysis of the relationship between the column density of gas (in all major forms) and the intensity of cosmic ) γ-rays in the Galaxy. It is concluded that most of the features observed in the gamma-ray map can be explained in terms of cosmic-ray interactions with the gas in the ISM, with molecular hydrogen playing an important role. The cosmic-ray intensity in the important production regions appears to be roughly independent of galactocentric distance, R, for l: 65–100° and to fall off slowly with R for l:100–180°.