NTRS - NASA Technical Reports Server

Back to Results
X-ray emission from clusters and groups of galaxiesRecent major advances in x-ray imaging and spectroscopy of clusters have allowed the determination of their mass and mass profile out to approximately 1/2 the virial radius. In rich clusters, most of the baryonic mass is in the gas phase, and the ratio of mass in gas/stars varies by a factor of 2-4. The baryonic fractions vary by a factor of approximately 3 from cluster to cluster and almost always exceed 0.09 h50-[3/2] and thus are in fundamental conflict with the assumption of Omega = 1 and the results of big bang nucleosynthesis. The derived Fe abundances are 0.2-0.45 solar, and the abundances of O and Si for low redshift systems are 0.6-1.0 solar. This distribution is consistent with an origin in pure type II supernova. The amount of light and energy produced by these supernovae is very large, indicating their importance in influencing the formation of clusters and galaxies. The lack of evolution of Fe to a redshift of z approximately 0.4 argues for very early enrichment of the cluster gas. Groups show a wide range of abundances, 0.1-0.5 solar. The results of an x-ray survey indicate that the contribution of groups to the mass density of the universe is likely to be larger than 0.1 h50-2. Many of the very poor groups have large x-ray halos and are filled with small galaxies whose velocity dispersion is a good match to the x-ray temperatures.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Mushotzky, R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 22, 2013
Publication Date
January 6, 1998
Publication Information
Publication: Proceedings of the National Academy of Sciences of the United States of America
Volume: 95
Issue: 1
ISSN: 0027-8424
Subject Category
Life Sciences (General)
Distribution Limits

Available Downloads

There are no available downloads for this record.
No Preview Available