F814W-z vs F775W-z

From: Marc Postman (postman@stsci.edu)
Date: Wed Jan 18 2006 - 07:16:41 PST

  • Next message: Nino Panagia: "Re: F814W-z vs F775W-z"

    In preparation for discussion tomorrow (is the next telecon tomorrow?),
    here are some predicted colors as a function of redshift and SED for
    i775-z850 vs. F814W-z850 (in the AB mag system). The qualitative trends
    are similar but, of course, the i-z color has quantitatively larger and
    the (i775-z850) gap between z>1 galaxies and z<0.7 galaxies is also
    quantitatively larger. This is important from the perspective of
    isolating the red sequence in clusters without extensive redshift
    information. For example, at zmag of 24, the foreground field galaxy
    population has (i775-z850) colors in the range -0.1 < (i775-z850) <
    0.55. This is well below where the red sequence lies for z > 1 but only
    a few tenths of a mag below where the RCS lies in (I814-z850). While we
    could still distinguish the RCS in (I814-z850), using (i775-z850) would
    be preferable, I think.




    ------------------------------------------------------------------------
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    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



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