Strong lensing efficiency of galaxy clusters in dark energy cosmologies

¹ Zentrum für Astronomie der Universität Heidelberg, ITA, Albert-Überle-Str. 2, 69120 Heidelberg, Germany e-mail: massimo.meneghetti@ita.uni-heidelberg.de
² Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35120 Padova, Italy
³ Max-Planck-Institut für Teoretische Astrophysik, 85748 Garching, Germany
⁴ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁵ SISSA/ISAS, via Beirut 4, 34014 Trieste, Italy
⁶ INFN, Sezione di Trieste, via Valerio 2, 34127 Trieste, Italy
⁷ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720, USA

Received: 5 May 2004
Accepted: 11 June 2005

Abstract

We study the efficiency for producing strong gravitational lensing events of galaxy clusters numerically simulated in different dark-energy cosmologies with constant and time-variable equation of state, and we compare the results with those obtained in “standard” ΛCDM and OCDM models. Our main results are (1) that the expected abundance of gravitational arcs with large length-to-width ratio depends on the equation of state of dark energy at the epoch of formation of the halo; and (2) that the high sensitivity of strong-lensing cross sections of galaxy clusters to dynamical processes like mergers, which was found in earlier studies, varies substantially between different cosmologies, being stronger for models in which halos are less concentrated. As expected, the largest differences in the lensing optical depth occur at intermediate and high redshift.