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Astron. Astrophys. 330, 1-9 (1998)

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Arc statistics with realistic cluster potentials

IV. Clusters in different cosmologies

Matthias Bartelmann 1, Andreas Huss 1, Jörg M. Colberg 1, Adrian Jenkins 2 and Frazer R. Pearce 2

1 Max-Planck-Institut für Astrophysik, P.O. Box 1523, D-85740 Garching, Germany
2 Physics Department, University of Durham, Durham DH1 3LE, UK

Received 21 July 1997 / Accepted 17 October 1997

Abstract

We use numerical simulations of galaxy clusters in different cosmologies to study their ability to form large arcs. The cosmological models are: Standard CDM (SCDM; [FORMULA], [FORMULA]); [FORMULA] CDM with reduced small-scale power (parameters as SCDM, but with a smaller shape parameter of the power spectrum); open CDM (OCDM; [FORMULA], [FORMULA]); and spatially flat, low-density CDM ([FORMULA] CDM; [FORMULA], [FORMULA]). All models are normalised to the local number density of rich clusters. Simulating gravitational lensing by these clusters, we compute optical depths for the formation of large arcs. For large arcs with length-to-width ratio [FORMULA], the optical depth is largest for OCDM. Relative to OCDM, the optical depth is lower by about an order of magnitude for [FORMULA] CDM, and by about two orders of magnitude for S/ [FORMULA] CDM. These differences originate from the different epochs of cluster formation across the cosmological models, and from the non-linearity of the strong lensing effect. We conclude that only the OCDM model can reproduce the observed arc abundance well, while the other models fail to do so by orders of magnitude.

Key words: galaxies: clusters: general – cosmology: dark matter – cosmology: gravitational lensing – cosmology: large-scale structure of Universe

Send offprint requests to: Matthias Bartelmann

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© European Southern Observatory (ESO) 1998

Online publication: January 8, 1998
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