Issue A&A Volume 481, Number 3, April III 2008 Page(s) 615 - 627 Section Cosmology (including clusters of galaxies) DOI 10.1051/0004-6361:20077306 Published online 04 February 2008

A&A 481, 615-627 (2008)
DOI: 10.1051/0004-6361:20077306

Integral field spectroscopy of four lensed quasars: analysis of their neighborhood and evidence for microlensing

T. Anguita¹, C. Faure¹, A. Yonehara^{1, 2}, J. Wambsganss¹, J.-P. Kneib³, G. Covone⁴, and D. Alloin<sup>5

1</sup>  Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
    e-mail: tanguita@ari.uni-heidelberg.de
²  JSPS Postdoctoral Fellowships for Research Abroad
³  Laboratoire d'Astrophysique de Marseille, UMR 6110, CNRS-Université de Provence, BP 8, 13376 Marseille Cedex 12, France
⁴  Universitá Federico II, Department of Physical Sciences, via Cinthia 9, 80126 Naples, Italy
⁵  AIM, CEA/DSM-CNRS-Université Paris 7, SAp, Bât. 709, CE Saclay, l'Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France

(Received 15 February 2007 / Accepted 7 January 2008)

Abstract
Context. Gravitationally lensed quasars constitute an independent tool to derive the Hubble constant through the time-delays of their different images; they offer as well the opportunity to study the mass distribution and interstellar medium of their lensing galaxies and, through microlensing due to stars in their lensing galaxy, they also allow one to study details of the emitting source.
Aims. For such studies, one needs to have an excellent knowledge of the close environment of the lensed images in order to model the lensing potential: this means, ideally, observational data over a large field-of-view and spectroscopy at high spatial resolution.
Methods. We present VIMOS integral field observations of 27´´ 27´´ fields of view around four lensed quasars: HE 0230-2130, RX J0911.4 + 0551, H 1413 + 117 and B 1359 + 154. Using the low, medium and high resolution modes, we study the quasar images and the quasar environments. Because of the complexity of the reduction of integral field datasets, we provide a detailed report of the data reduction.
Results. Comparison between the quasar spectra of the different images reveals differences for HE 0230-2130, RX J0911.4 + 0551 and H 1413+117: flux ratios between the images of the same quasar are different when measured in the emission lines and in the continuum. We have also measured the redshifts of galaxies in the neighborhood of HE 0230-2130 and RX J0911.4 + 0551 which possibly contribute to the total lensing potential, given their close proximity to the line-of-sight toward the quasars.
Conclusions. A careful analysis reveals that microlensing is the most natural explanation for the (de)magnification of the continuum emitting region of the background sources. In HE 0230-2130, image D is likely to be affected by microlensing magnification; in RX J0911.4+0551, images A1 and A3 are likely to be modified by microlensing de-magnification and in H 1413+117, at least image D is affected by microlensing. We have not been able to recover any microlensing information or galaxies close to the line-of-sight in the neighborhood of B 1359+154.

Key words: gravitational lensing -- techniques: spectroscopic -- quasars: general -- cosmology: observations

© ESO 2008

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