THE SHARC SURVEY: AN UPDATE
M ULMER (a), C ADAMI (a), R PILDIS (a), A ROMER (b),
R NICHOL (b), B HOLDEN (c), R KRON (c)
(a) Dept. of Physics and Astronomy, Northwestern University
Evanston, IL 60208-2900, USA
(b) Dept. of Physics, Carnegie Mellon University Pittsburgh, PA 15213
(c) Dept. of Astronomy \& Astrophysics, University of Chicago, Chicago, IL 60637
Abstract:
We summarize the results of the Bright SHARC (Serendipitous High-redshift
Archival ROSAT Cluster) survey (http://www.astro.nwu.edu/sharc). This is a
search for distant X-ray bright clusters, which must be corrected for
completeness in order to convert these results into a luminosity function. We
have completed a thorough simulation of the SHARC survey. We show that our new
improved results have produced no major change to the results of the recently
published paper of Nichol {\em et al.} on cluster luminosity evolution.
Besides
statistics, the uncertainty in the luminosity function derived from X-ray
surveys is large, because we do not know the distribution of
X-ray cluster morphologies at high redshift. Our simulations show that to fully
understand the completeness of deep surveys, the distribution of the shapes of
the clusters must be understood. For, sharply peaked or highly elliptical
clusters are the easiest to detect. Beyond the Bright SHARC, we have initiated
a search for more distant X-ray luminous clusters. We have found
preliminary evidence
for the detection of up to four high-redshift X-ray luminous cluster.