2001/11/08 by B. W. Fairley, L. R. Jones, D. A. Wake +5 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2002.05121.x
published as Mon.Not.Roy.Astron.Soc. 330 (2002) 755 · Accepted for publication in MNRAS
arxiv created 2001/11/08 · openalex publication_date 2002/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Accepted.....................; Received.....................; in original form....................... We present initial results from a wide–field, multi–colour imaging project, designed to study galaxy evolution in X-ray selected clusters at intermediate (z ∼ 0.25) and high redshifts (z ∼ 0.5). In this paper we give blue galaxy fractions from eight X-ray selected clusters, drawn from a combined sample of three X-ray surveys. We find that all the clusters exhibit excess blue galaxy populations over the numbers observed in local systems, though a large scatter is present in the results. We find no significant correlation of blue fraction with redshift at z>0.2 although the large scatter could mask a positive trend. We also find no systematic trend of blue fraction with X-ray luminosity. We show that the blue fraction is a function of (a) radius within a cluster, (b) absolute magnitude and (c) the passbands used to measure the colour. We find that our blue fractions (fb) from galaxy colours close to restframe (U −B)0, fb ∼ 0.4, are systematically higher than those from restframe (B − V)0 colours, fb ∼ 0.2. We conclude this effect is real, may offer a partial explanation of the widely differing