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OSO 8 X-ray spectra of clusters of galaxies. I - Observations of twenty clusters: Physical correlationsOSO 8 X-ray spectra from 2 to 20 keV have been analyzed for 26 clusters of galaxies. For 20 clusters temperatures, emission integrals, iron abundances, and low-energy absorption measurements are presented. The data give, in general, better fits to thermal bremsstrahlung than to power-law models. Eight clusters have positive iron emission-line detections at the 90% confidence level, and all 20 cluster spectra are consistent with Fe/H = 0.000014 by number with the possible exception of Virgo. Thus it is confirmed that X-ray emission in this energy band is predominantly thermal radiation from hot intracluster gas rather than inverse Compton radiation. Physical correlations between X-ray spectral parameters and other cluster properties are examined. It is found that (1) the X-ray temperature is approximately proportional to the square of the velocity dispersion of the galaxies; (2) the emission integral is a strong function of the X-ray temperature; (3) the X-ray temperature and emission integral are better correlated with cluster central-galaxy density than with richness; and (4) the fraction of galaxies which are spirals is correlated with the observed ram pressure in the cluster core.
Document ID
19780068544
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mushotzky, R. F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Serlemitsos, P. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Boldt, E. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Holt, S. S. (NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics, Greenbelt, Md., United States)
Smith, B. W. (NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics, Greenbelt; Maryland, University, College Park, Md., United States)
Date Acquired
August 9, 2013
Publication Date
October 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
ASTRONOMY
Distribution Limits
Public
Copyright
Other