Parameterised models for the lensing cluster Abell 1689

Free access article

Issue		A&A Volume 383, Number 1, February III 2002


Page(s)		118 - 124
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20011722

A&A 383, 118-124 (2002)
DOI: 10.1051/0004-6361:20011722

Parameterised models for the lensing cluster Abell 1689

L. J. King^{1, 2}, D. I. Clowe² and P. Schneider^{2, 1}

¹ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str 1, Garching bei München, Germany
² Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany

(Received 20 July 2001 / Accepted 3 December 2001 )

Abstract
Here we apply a recently developed maximum likelihood method for determining best-fit parameterised lens models to observations of the rich lensing cluster Abell 1689. The observations that we use were taken with the ESO/MPG Wide Field Imager. The wide field-of-view enables us to use the weakly lensed images of faint background objects on an unsurpassed range of scales, $0.12\,h^{-1}\,{\rm Mpc} < R < 1.8\,h^{-1}\,{\rm Mpc}$ from the cluster centre, to determine best-fit models for the 1-parameter singular isothermal sphere (SIS), 2-parameter general power-law and NFW models, and 3-parameter singular isothermal ellipsoid (SIE). The best-fit SIS has an Einstein radius $\theta_{\rm E}=0\hbox{$.\!\!^{\prime}$ }37$ $(0.043\,h^{-1}\,{\rm Mpc})$ i.e. a velocity dispersion $\sigma_{\rm 1D}=1028^{+35}_{-42}\,{\rm km\,s^{-1}}$ in an $\Omega=1.0$ , $\Lambda=0.0$ cosmology. For the best-fit NFW profile, the virial radius $r_{200}=1.14\,h^{-1}\,{\rm Mpc}$ and the concentration parameter c=4.7, giving a virial mass $M_{200}=5.7\times 10^{14}\,h^{-1}\,M_{\odot}$ . At q=0.88, the slope of the best-fit power-law model is slightly flatter than isothermal ( q=1.0), indicating that the galaxies most important in the fitting procedure lie inside the scale radius $r_{\rm s}$ . By fitting an SIE, the deviation of the projected mass distribution from circular symmetry is evident, with a best-fit axial ratio f=0.74.

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

Offprint request: L. J. King, lindsay@astro.uni-bonn.de

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