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Absorption and Production of Soft X-Rays in the Galaxy

Published online by Cambridge University Press:  14 August 2015

S. Hayakawa
S. Hayakawa*
Affiliation:
Nagoya University, Nagoya, Japan

Abstract

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The column densities of interstellar hydrogen to X-ray sources derived from their spectra are compared with those obtained from 21 cm radio observations. Referring to several observed results on Cyg X-2, Cygnus Loop etc., the interpretation of the low energy cut-off of the spectrum in terms of the interstellar absorption is subject to ambiguities due to a modification of the emission spectrum by Compton scattering in the sources and the contribution of emission lines.

The result of soft X-ray sky surveys indicates that the diffuse component of soft X-rays consists of the extragalactic and the galactic components. The former has a hard component with a power law spectrum and a soft component which may be represented by an exponential spectrum. The galactic component is so soft that its spectrum may also be explained by thermal bremsstrahlung of temperature of about 0.1 keV. Its generation rate may account for the heating and ionization of interstellar matter. It is suggested that galactic diffuse soft X-rays are produced by active stars of a rather high number density.

Type
Part IV: Interstellar Medium and Soft X-Ray Background
Information
Symposium - International Astronomical Union , Volume 55: X- and Gamma-Ray Astronomy , 1973 , pp. 235 - 249
Copyright
Copyright © Reidel 1973 

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