Selection effects on X-ray and strong-lensing clusters in various cosmologies

Zentrum für Astronomie, ITA, Universität Heidelberg, Albert-Überle-Str. 2, 69120 Heidelberg, Germany e-mail: cosimo@ita.uni-heidelberg.de

Received: 30 March 2007
Accepted: 31 July 2007

Abstract

Galaxy clusters are hotter and more X-ray luminous than in quiescence while they undergo major mergers, which also transiently increase their strong-lensing efficiency. We use semi-analytic models for both effects to study how cluster dynamics in different dark-energy models affects the X-ray selected cluster population and its strong-lensing optical depth. We find that mergers increase the number of observable X-ray clusters by factors of a few and considerably broaden their redshift distribution. Strong-lensing optical depths are increased by a very similar amount. Quite independent of cosmology, X-ray bright clusters above a flux limit of produce ~ of the strong-lensing optical depth, and only ~ above a flux limit of if mergers are taken into account.