Published by
EDP Sciences
EDP Sciences Journals List
Subscriber Authentication Point
Home All issues Volume 501/ 2 Article
Free access
Issue A&A
Volume 501, Number 2, July II 2009
Page(s) 475 - 484
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361/200911963
Published online 19 May 2009

A&A 501, 475-484 (2009)
DOI: 10.1051/0004-6361/200911963

The mass profile of early-type galaxies in overdense environments: the case of the double source-plane gravitational lens SL2SJ02176-0513

H. Tu1, 2, 3, R. Gavazzi2, 3, 4, M. Limousin5, 6, 7, R. Cabanac5, P. J. Marshall4, B. Fort2, 3, T. Treu4, R. Péllo8, E. Jullo6, 9, J.-P. Kneib6, 10, and J.-F. Sygnet2, 3

1  Physics Department & Shanghai Key Lab for Astrophysics, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, PR China
    e-mail: tuhong@shnu.edu.cn
2  CNRS, UMR7095, Institut d'Astrophysique de Paris, 98bis Bd Arago, 75014, Paris, France
3  UPMC Univ. Paris 6, UMR7095, Institut d'Astrophysique de Paris, 98bis Bd Arago, 75014, Paris, France
4  Department of Physics, University of California, Santa Barbara, CA 93106, USA
5  Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 57 avenue d'Azereix, 65000 Tarbes, France
6  OAMP, Laboratoire d'Astrophysique de Marseille - UMR 6110, Traverse du siphon, 13012 Marseille, France
7  Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
8  Laboratoire d'Astrophysique de Toulouse-Tarbes, CNRS-UMR 5572, and Univ. Paul Sabatier, 31400 Toulouse, France
9  European Southern Observatory, Alonso de Cordoba, Santiago, Chile
10  Department of Astronomy, California Institute of Technology, 105-24, Pasadena, CA91125, USA

Received 27 February 2009 / Accepted 13 April 2009

Abstract
Context. The Strong Lensing Legacy Survey (SL2S) provides a sample of the strong lensing events associated with massive distant galaxies, some of which lie in the outskirts of galaxy groups and clusters.
Aims. We investigate the internal structure of early-type galaxies in overdense environments, where tidal forces are expected to alter dark matter haloes of infalling galaxies.
Methods. SL2SJ02176-0513 is a remarkable lens for the presence of two multiply-imaged systems at different redshifts lensed by a foreground massive galaxy at $z_{\rm lens}$ = 0.656: a bright cusp arc at $z_{\rm arc}$ = 1.847 and an additional double-image system at an estimated redshift of $z_{\rm dbl}$ ~ 2.9 based on photometry and lensing geometry. The system is located about 400 kpc away from the centre of a massive group of galaxies. Mass estimates for the group are available from X-ray observations and satellite kinematics. Multicolour photometry provides an estimate of the stellar mass of the main lens galaxy. The lensing galaxy is modelled with two components (stars and dark matter), and we include the perturbing effect of the group environment and all available constraints.
Results. We find that classic lensing degeneracies, e.g. between external convergence and mass density slope, are significantly reduced with respect to standard systems and infer tight constraints on the mass density profile: (i) the dark matter content of the main lens galaxy is in line with that of typical galaxies $f_{\rm dm}({<}R_{\rm e})=0.41^{+0.09}_{-0.06}$; (ii) the required mass associated with the dark matter halo of the nearby group is consistent with X-ray $(\sigma_{\rm grp}=550^{+130}_{-240})$; (iii) accounting for the group contribution in the form of an external convergence, the slope of the mass density profile of the main lens galaxy alone is found to be $\alpha=-1.03^{+0.22}_{-0.16}$, consistent with the isothermal ($\alpha$ = -1) slope.
Conclusions. We demonstrate that multiple source plane systems together with good ancillary dataset can be used to disentangle local and environmental effects.


Key words: gravitational lensing -- Galaxy: general -- dark matter



© ESO 2009

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.