Parameterised models for the lensing cluster Abell 1689

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

Corresponding author: L. J. King, lindsay@astro.uni-bonn.de

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, 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 i.e. a velocity dispersion in an , cosmology. For the best-fit NFW profile, the virial radius and the concentration parameter , giving a virial mass . At , the slope of the best-fit power-law model is slightly flatter than isothermal (), indicating that the galaxies most important in the fitting procedure lie inside the scale radius r_s. By fitting an SIE, the deviation of the projected mass distribution from circular symmetry is evident, with a best-fit axial ratio .