A search for clusters and groups of galaxies on the line of sight towards 8 lensed quasars^*

¹ Universidad Católica de Chile, Departamento de Astronomia y Astrofisica, Casilla 306, Santiago 22, Chile e-mail: cfaure@astro.puc.cl
² European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile
³ URA2052CNRS/SAp/CEA, L'Orme des Merisiers, 91191 Gif-sur-Yvette, France
⁴ Observatoire Midi-Pyrénées, UMR 5572, 14 avenue Édouard Belin, 31400 Toulouse, France
⁵ Caltech Astronomy Department, Mail Code 105-24, Pasadena, CA 91125, USA
⁶ Institut d'Astrophysique et de Géophysique, Faculté des Sciences, Université de Liège, Allée du 6 août, 17, B5C, Liège 1, Belgium

Received: 8 March 2004
Accepted: 19 May 2004

Abstract

In this paper we present new ESO/VLT FORS1 and ISAAC images of the fields around eight gravitationally lensed quasars: CTQ 414, HE 0230-2130, LBQS 1009-0252, B 1030+074, HE 1104-1805, B 1359+154, H 1413+117 and HE 2149-2745. When available and deep enough, HST/WFPC2 data were also used to infer the photometric redshifts of the galaxies around the quasars. The search of galaxy overdensities in space and redshift, as well as a weak-shear analysis and a mass reconstruction are presented in this paper. We find that there are most probably galaxy groups towards CTQ 414, HE 0230-2130, B 1359+154, H 1413+117 and HE 2149-2745, with masses ≤  h^-1. Considering its photometric redshift, the galaxy group discovered in the field around HE 1104-1805 is associated with the quasar rather than with the lensing potential.