Galaxy distribution in Butcher-Oemler clusters

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/164351· OSTI ID:6931855

Thompson, L A

The galaxy distribution in six Butcher-Oemler clusters is analyzed in order to obtain separate core radii for the blue galaxies and for the red E-sequence galaxies. By fitting these distributions with isothermal spheres via maximum-likelihood techniques, the core radius for the blue galaxies is shown to be nearly three times that of the red galaxies. While the general trend of the blue/red galaxy segregation was noticed by Butcher and Oemler, the analysis is presented here places this result on firm statistical ground. A test for luminosity segregation gives only marginally significant results, while a comparison of differential luminosity functions shows that blue galaxies, in their quiescent state, are likely to be about 1 mag fainter than red E-sequence galaxies. When combined with each other, the two previous results imply that mass segregation cannot explain the broad blue galaxy distribution. A discussion of dynamical considerations particularly the relative velocity dispersions of blue and red galaxies - is included to show how the blue/red galaxy segregation might arise. 17 references.

• Research Organization: Hawaii Univ., Honolulu
• OSTI ID: 6931855
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 306; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DISTRIBUTION
GALAXY CLUSTERS
ISOTHERMAL PROCESSES
LUMINOSITY
MASS DISTRIBUTION
MORPHOLOGY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPATIAL DISTRIBUTION