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


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.


Energy Range Fair Agreement Spiral Galaxy Background Component Distant Galaxy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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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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