Astronomy and Astrophysics, volume 407, 845-854 (2003/9-1)
Stacking clusters in the ROSAT All-Sky Survey.
BARTELMANN M. and WHITE S.D.M.
Abstract (from CDS):
Ongoing and planned wide-area surveys at optical and infrared wavelengths should detect a few times 105 galaxy clusters, roughly 10% of which are expected to be at redshifts >0.8. We investigate what can be learned about the X-ray emission of these clusters from the ROSAT All-Sky Survey. While individual clusters at redshifts >0.5 contribute at most a few photons to the survey, a significant measurement of the mean flux of cluster subsamples can be obtained by stacking cluster fields. We show that the mean X-ray luminosity of clusters with mass M>2x1014h–1M☉ selected from the Sloan Digital Sky Survey should be measurable out to redshift unity with signal-to-noise >10, even if clusters are binned with Δz=0.1 and Δln(M)∼0.3. For such bins, a suitably chosen hardness ratio allows the mean temperature of clusters to be determined out to z∼0.7 with a relative accuracy of ΔT/T≲0.15 for M>1014h–1M☉.
surveys - galaxies: clusters: general - X-rays: galaxies