EDP Sciences
Free access
Issue
A&A
Volume 407, Number 3, September I 2003
Page(s) 845 - 854
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20030991


A&A 407, 845-854 (2003)
DOI: 10.1051/0004-6361:20030991

Stacking clusters in the ROSAT All-Sky Survey

M. Bartelmann and S. D. M. White

Max-Planck-Institut für Astrophysik, PO Box 1317, 85741 Garching, Germany
(Received 2 October 2002 / Accepted 25 June 2003)

Abstract
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 $\gtrsim$ 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 $\gtrsim$ 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 $M\gtrsim2\times10^{14}\,h^{-1}M_\odot$ selected from the Sloan Digital Sky Survey should be measurable out to redshift unity with signal-to-noise $\gtrsim$ 10, even if clusters are binned with $\Delta z=0.1$ and $\Delta\ln M\sim0.3$. For such bins, a suitably chosen hardness ratio allows the mean temperature of clusters to be determined out to $z\sim0.7$ with a relative accuracy of $\Delta
T/T\lesssim0.15$ for $M>10^{14}\,h^{-1}M_\odot$.


Key words: surveys -- galaxies: clusters: general -- X-rays: galaxies

Offprint request: M.Bartelmann, msb@mpa-garching.mpg.de

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