Volume 524, December 2010
|Number of page(s)||11|
|Section||Cosmology (including clusters of galaxies)|
|Published online||25 November 2010|
Strong lensing as a probe of the mass distribution beyond the Einstein radius
Mass and light in SL2S J08544-0121, a galaxy group at z = 0.35
Laboratoire d’Astrophysique de Marseille, UMR 6610,
CNRS-Université de Provence, 38 rue
Frédéric Joliot-Curie, 13388
Marseille Cedex 13,
2 Laboratoire d’Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 57 avenue d’Azereix, 65000 Tarbes, France
3 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
4 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
5 Durham University, Physics and Astronomy Department, South Road, Durham DH3 1LE, UK
6 Department of Astronomy, California Institute of Technology, 105-24 Pasadena, CA 91125, USA
7 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
8 Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748 Garching, Germany
9 CNRS, UMR 7095, Institut d’Astrophysique de Paris, 75014 Paris, France
10 UPMC Université Paris 06, UMR 7095, Institut d’Astrophysique de Paris, 75014 Paris, France
11 Laboratoire d’Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 avenue Edouard Belin, 31400 Toulouse, France
Received: 22 June 2010
Accepted: 9 September 2010
Strong lensing has been employed extensively to obtain accurate mass measurements within the Einstein radius. We here use strong lensing to probe mass distributions beyond the Einstein radius. We consider SL2S J08544-0121, a galaxy group at redshift z = 0.35 with a bimodal light distribution and with a strong lensing system located at one of the two luminosity peaks separated by ~54″. The main arc and the counter-image of the strong lensing system are located at ~5″ and ~8″ from the lens galaxy centre. We find that a simple elliptical isothermal potential cannot satisfactorily reproduce the strong lensing observations. However, with a mass model for the group built from its light-distribution with a smoothing factor s and a mass-to-light ratio M/L, we obtain an accurate reproduction of the observations. We find M/L = 98 ± 27 (i band, solar units, not corrected for evolution) and s = 20″ ± 9 (2σ confidence level). Moreover, we use weak lensing to independently estimate the mass of the group, and find a consistent M/L in the range 66-146 (1-σ confidence level). This suggests that light is a good tracer of mass. Interestingly, this also shows that a strong lensing-only analysis (on scales of ~10″) can constrain the properties of nearby objects (on scales of ~100″). We characterise the type of perturbed strong lensing system that allows such an analysis: a non dominant strong lensing system used as a test particle to probe the main potential. This kind of analysis needs to be validated with other systems because it could provide a quick way of probing the mass distribution of clusters and groups. This is particularly relevant in the context of forthcoming wide-field surveys, which will yield thousands of strong lenses, some of which perturbed enough to pursue the analysis proposed in this paper.
Key words: gravitational lensing: strong / dark matter
Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Also based on HST data, program 10876 and Keck telescope data.
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.