Volume 559, November 2013
|Number of page(s)||22|
|Section||Cosmology (including clusters of galaxies)|
|Published online||22 November 2013|
SARCS strong-lensing galaxy groups
1 Departamento de Física y Astronomía, Universidad de Valparaíso, 1111 Avda. Gran Bretaña, Valparaíso, Chile
2 Aix Marseille Universit, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
3 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
4 Centro de Investigaciones de Astronomía, AP 264, 5101-A Mérida, Venezuela
5 Kavli Institute for Cosmological Physics, U. of Chicago, 5640 S. Ellis Ave., IL-60637 Chicago, USA
6 Kavli IPMU, University of Tokyo, 5-1-5 Kashiwanoha, 277-8583 Kashiwa, Japan
7 CNRS, Institut de Recherche en Astrophysique et Planétologie, 57 avenue d’Azereix, 65000 Tarbes, France
8 Institut d’Astrophysique de Paris, UMR 7095 CNRS & Université Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
9 Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, V. Mackenna 4860, 782-0436 Macul, Santiago, Chile
Received: 15 January 2013
Accepted: 21 August 2013
We present the weak-lensing and optical analysis of the SL2S-ARCS (SARCS) sample of strong-lensing candidates. The sample is based on the Strong Lensing Legacy Survey (SL2S), a systematic search of strong-lensing systems in the photometric Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The SARCS sample focusses on arc-like features and is designed to contain mostly galaxy groups. We briefly present the weak-lensing methodology that we used to estimate the mass of the SARCS objects. Among 126 candidates, we obtained a weak-lensing detection (at the 1σ level) for 89 objects with velocity dispersions of the singular isothermal sphere mass model (SIS) ranging from σSIS ~ 350 km s-1 to ~1000 km s-1 with an average value of σSIS ~ 600 km s-1, corresponding to a rich galaxy group (or poor cluster). From the galaxies belonging to the bright end of the group’s red sequence (Mi < −21), we derived the optical properties of the SARCS candidates. We obtained typical richnesses of N ~ 5−15 galaxies and optical luminosities of L ~ 0.5−1.5 × 1012 L⊙ (within a radius of 0.5 Mpc). We used these galaxies to compute luminosity density maps, from which a morphological classification reveals that a large fraction of the sample (~45%) are groups with a complex light distribution, either elliptical or multi-modal, suggesting that these objects are dynamically young structures. We finally combined the lensing and optical analyses to define a sample of the 80 most secure group candidates, i.e. weak-lensing detection and over-density at the lens position in the luminosity map, to remove false detections and galaxy-scale systems from the initial sample. We use this reduced sample to probe the optical scaling relations in combination with a sample of massive galaxy clusters. We detect the expected correlations over the probed range in mass with a typical scatter of ~25% in σSIS at a given richness or luminosity, making these scaling laws interesting mass proxies.
Key words: gravitational lensing: weak / cosmology: observations / dark matter / galaxies: groups: general
Table 2 and Appendix A are available in electronic form at http://www.aanda.org
© ESO, 2013
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