Egal overdensity vs redshift offset from cluster

From: Marc Postman (postman@stsci.edu)
Date: Fri Jan 13 2006 - 08:34:37 PST

  • Next message: Saul Perlmutter: "Re: Egal overdensity vs redshift offset from cluster"

    Saul et al.,

    Here is a plot that may demonstrate the point that early type galaxies
    are strongly localized in the clusters for z > 1. This is a histogram
    of spectroscopic redshifts for the clusters RXJ0910+54, RXJ1252-29, and
    CL0848+44 (which are at z=1.10, 1.24, and 1.27, respectively). The red
    histo is E+S0 galaxies and the blue histo is Sa or later. Relative to
    the spikes seen in the field, the E+S0 overdensity in the cluster is
    about a factor of 10 whereas the Sa+ overdensity is at best a factor of
    2. There may be some selection effects in the spectroscopic selection
    to slightly favor early types, however. But these effects, if corrected
    for, might only increase the Sa+ peak at dz=0 by about 20 - 30% (but
    would also probably increase the spikes in the field as well so that
    the overall enhancement factor would probably still be only about a
    factor of 2). The redshift range covered by this plot is 0.9 < z <
    1.47.

    Marc




    -----------------------------------------------------------------
    Marc Postman Email: postman@stsci.edu
    STScI - CMO Phone: +1-410-338-4340
    3700 San Martin Drive Fax: +1-410-338-4424
    Baltimore, MD 21218 U.S.A. http://www.stsci.edu/~postman



    This archive was generated by hypermail 2.1.4 : Fri Jan 13 2006 - 08:36:15 PST