Weak lensing mass reconstruction of the galaxy cluster Abell 209 ^*,**

¹ INAF / Osservatorio Astrofisico di Catania via S. Sofia, 78, 95123 Catania, Italy e-mail: paulin@in2p3.fr,[Vincenzo.Antonuccio;Ugo.Becciani]@oact.inaf.it
² INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy

Received: 21 December 2006
Accepted: 5 February 2007

Abstract

Context. Weak lensing applied to deep optical images of clusters of galaxies provides a powerful tool to reconstruct the distribution of the gravitating mass associated to these structures.

Aims. We use the shear signal extracted by an analysis of deep exposures of a region centered around the galaxy cluster ABCG 209, at redshift , to derive both a map of the projected mass distribution and an estimate of the total mass within a characteristic radius.

Methods. We use a series of deep archival R-band images from CFHT-12k, covering an area of ~deg². We determine the shear of background galaxy images using a new implementation of the modified Kaiser-Squires-Broadhurst KSB+ pipeline for shear determination, which we has been tested against the “Shear TEsting Program 1 and 2'' simulations. We use mass aperture statistics to produce maps of the 2 dimensional density distribution, and parametric fits using both Navarro-Frenk-White and singular-isothermal-sphere profiles to constrain the total mass.

Results. The projected mass distribution shows a pronounced asymmetry, with an elongated structure extending from the SE to the NW. This is in general agreement with the optical distribution previously found by other authors. A similar elongation was previously detected in the X-ray emission map, and in the distribution of galaxy colours. The circular NFW mass profile fit gives a total mass of inside the virial radius Mpc.

Conclusions. The weak lensing profile reinforces the evidence for an elongated structure of ABCG 209, as previously suggested by studies of the galaxy distribution and velocities.