Cosmic γ rays and the mass of gas in the Galaxy
Abstract
We make the case that the cosmic-ray particles that produce cosmic γ-rays in the 100-MeV region can penetrate most of the dense clouds of gas that seem to contain much of the mass of gas in the Galaxy. We determine a probable form for cosmic-ray intensity as a function of Galactic position and use the measured γ-ray intensities to derive the surface density of gas as a function of position. Our estimate of ~6 × 108 Msolar for the total mass of molecular hydrogen compared with 1 × 109 Msolar for atomic hydrogen in the inner Galaxy is a significant change in the contemporary perspective.
- Publication:
-
Nature
- Pub Date:
- April 1985
- DOI:
- 10.1038/314511a0
- Bibcode:
- 1985Natur.314..511B
- Keywords:
-
- Galactic Cosmic Rays;
- Galactic Nuclei;
- Gamma Ray Astronomy;
- Gas Density;
- Molecular Clouds;
- Carbon Monoxide;
- Galactic Structure;
- Hydrogen Clouds;
- Interstellar Chemistry;
- Mass Distribution;
- Molecular Excitation;
- Orion Nebula;
- Radial Distribution;
- Virial Theorem;
- Astrophysics