Astrophysics and Space Science

, Volume 4, Issue 1, pp 64–83 | Cite as

Correlation between the densities of X-ray sources and interstellar gas

  • M. Fujimoto
  • S. Hayakawa
  • T. Kato
Article

Abstract

The distribution of X-ray sources in our galaxy is obtained, assuming that the absolute X-ray luminosities of these sources are the same. The distribution is found to be in good correlation with the distribution of interstellar gas. The density of X-ray sources is nearly proportional to the square density of gas. This indicates that X-ray sources are comparatively young. The relation between the densities of X-ray sources and gas allows us to estimate the X-ray intensities of various objects such as Magellanic Clouds and Andromeda nebula, and also to obtain the average X-ray luminosity of spiral galaxies. The latter should increase as the age of a galaxy decreases, since the amount of gas decreases as the galaxy evolves. Under the assumptions that the gas density is inversely proportional to the age and that galaxies older thant0/30 are visible in X-rays, wheret0 is the present age of the universe, the contribution of X-ray sources in distant galaxies to the background component is calculated. The intensity and the spectrum of the background component of X-rays thus obtained are in fair agreement with observed ones in the energy range between 1 and 4 keV but significantly deviate from the latter at high energies.

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Copyright information

© D. Reidel Publishing Company, Dordrecht-Holland 1969

Authors and Affiliations

  • M. Fujimoto
    • 1
  • S. Hayakawa
    • 1
  • T. Kato
    • 1
  1. 1.Dept. of PhysicsNagoya UniversityNagoyaJapan

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