Strong lensing analysis of the cluster RCS0224-0002 at z = 0.77

Free access article

Issue		A&A Volume 471, Number 3, September I 2007


Page(s)		743 - 752
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20077594

A&A 471, 743-752 (2007)
DOI: 10.1051/0004-6361:20077594

Strong lensing analysis of the cluster RCS0224-0002 at z = 0.77

J. Rzepecki¹, M. Lombardi¹, P. Rosati¹, A. Bignamini², and P. Tozzi²

¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munich, Germany
e-mail: jrzepeck@eso.org
² INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy

(Received 3 April 2007 / Accepted 17 June 2007 )

Abstract
Aims.We present a detailed mass reconstruction of the cluster RCS0224-0002 at z=0.773 from the strong lensing features observed with HST/WFPC2.
Methods.The mass profile is reconstructed using a parametric approach. We introduce a novel method to fit extended multiple images based on the Modified Hausdorff Distance between observed arcs and the arcs reproduced by the model. We perform the detailed error analysis of the model parameter using the MCMC method.
Results.Our model reproduces all the observed strong lensing features of the RCS0224-0002 and predicts the redshift of one of the arcs systems to be $z\approx 2.65$ (the other system has an spectroscopic redshift of z=4.87). The reconstructed inner mass profile is well fitted by a non-singular isothermal sphere, rather than with an NFW model. Dark matter substructure, derived from the light distribution of the most luminous cluster members, is crucial for reproducing the complexity of the quadrupole image system, which could not be achieved otherwise. The reconstructed mass distribution closely follows the light, however it is significantly shifted from the X-ray emission of the gas. The mass of RCS0224-0002 derived from the lensing model, $\approx$ $2\times10^{14}\, M_\odot$ is in a very good agreement with the one obtained from the X-ray temperature measured with deep Chandra observations.

Key words: gravitational lensing -- galaxies: clusters: individual: RCS0224-0002

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