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a search for x-ray bright distant clusters of galaxiesWe present the results of a search for X-ray luminous distant clusters of galaxies. We found extended X-ray emission characteristic of a cluster toward two of our candidate clusters of galaxies. They both have a luminosity in the ROSAT bandpass of approximately equals 10(exp 44) ergs/s and a redshift greater than 0.5; thus making them two of the most distant X-ray clusters ever observed. Furthermore, we show that both clusters are optically rich and have a known radio source associated with them. We compare our result with other recent searches for distant X-ray luminous clusters and present a lower limit of 1.2 x 10(exp -7)/cu Mpc for the number density of such high-redshift clusters. This limit is consistent with the expected abundance of such clusters in a standard (b = 2) cold dark matter universe. Finally, our clusters provide important high-redshift targets for further study into the origin and evolution of massive clusters of galaxies.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Nichol, R. C.
(Northwestern University Evanston, IL, United States)
Ulmer, M. P.
(Northwestern University Evanston, IL, United States)
Kron, R. G.
(Fermi National Accelerator Laboratory, Batavia, IL United States)
Wirth, G. D.
(University of California, Santa Cruz, CA United States)
Koo, D. C.
(University of California, Santa Cruz, CA United States)
Date Acquired
August 16, 2013
Publication Date
September 10, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 432
Issue: 2
ISSN: 0004-637X
Subject Category
Funding Number(s)
Distribution Limits