Cosmic γ rays and the mass of gas in the Galaxy

The case is made that the cosmic-ray particles that produce cosmic gamma-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. A probable form for cosmic-ray intensity as a function of Galactic position is determined, and...

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Bibliographic Details
Published in:	Nature (London) Vol. 314; no. 6011; pp. 511 - 515
Main Authors:	Bhat, Chaman L, Issa, Mohamed R, Houston, Brian P, Mayer, Chris J, Wolfendale, Arnold W
Format:	Journal Article
Language:	English
Published:	London Nature Publishing 11-04-1985
Subjects:	Astronomy Characteristics and properties of the milky way Earth, ocean, space Exact sciences and technology Stellar systems. Galactic and extragalactic objects and systems. The universe Mass Galaxy Cosmic ray Gamma radiation Molecular cloud Interstellar gas
Online Access:	Get full text
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Summary:	The case is made that the cosmic-ray particles that produce cosmic gamma-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. A probable form for cosmic-ray intensity as a function of Galactic position is determined, and the measured gamma-ray intensities are used to derive the surface density of gas as a function of position. The estimate of about 600 million solar masses for the total mass of molecular hydrogen, compared with one billion solar masses for atomic hydrogen in the inner Galaxy, is a significant change in the contemporary perspective.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0028-0836 1476-4687
DOI:	10.1038/314511a0