A study of galaxy groups and clusters: the case for a clumpy intergalactic medium

Journal Article · Sun Jul 15 04:00:00 EDT 1973 · Astrophys. J., v. 183, no. 2, pp. 387-409

DOI:https://doi.org/10.1086/152235· OSTI ID:4316753

Silk, J; Tarter, J

A nonuniform model for a dense intergalactic medium ( OMEGA =1.5) is constructed under the assumption that all groups and clusters of galaxies are gravitationally bound by ionized gas. Catalogs by de Vaucoulcurs arad Abell are utilized to provide an almost complete sample of the spatial distribution of goups and clusters over a wide range of richness, and a distribution function is derived for galaxy goups and clusters as a function of velocity dispersion. A simple scaling law is applied to predict velocity dispersions for the very rich Abell clusters. Thermal bremsstrahlung emission from the intracluster gas accounts for the observed emission over 2-10 keV from several rich clusters, and also contributes up to 20 percent of the diffuse X-ray background over a considerable fraction of the observed range. The amount of X-ray emitting gas is restricted to a small fraction of the virial mass, with the remainder of the binding mass present as cooler ionized clouds. Available soft X-ray and ultraviolet diffuse background observations are used to define a narrow range of permissible temperatures and densities for these clouds. In particular, intergalactic clouds with temperatures 2 to 5x10/sup 5/ deg K and masses comparable to dwarf galaxies are not inconsiatent with present observations of groups and small clusters. This model is applied to calculate the probability of producing an absorption line in the spectrum of a distant object. (auth)

• Research Organization: University of California, Berkeley
• Sponsoring Organization: USDOE
• NSA Number: NSA-29-022057
• OSTI ID: 4316753
• Journal Information: Astrophys. J., v. 183, no. 2, pp. 387-409, Journal Name: Astrophys. J., v. 183, no. 2, pp. 387-409; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

*GALAXY CLUSTERS-- SPATIAL DISTRIBUTION
*INTERGALACTIC SPACE-- X RADIATION
ABSORPTION SPECTRA
BACKGROUND RADIATION
CONDENSATES
COSMIC X-RAY SOURCES
N56500* --Physics (Astrophysics & Cosmology)--Galaxies
SCALING LAWS GALAXY CLUSTERS