We present the weak lensing and optical analysis of the SL2S-ARCS ( SARCS ) sample of strong lens 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 focuses on arc-like features and is designed to contain mostly galaxy groups .
We briefly present the weak lensing methodology that we use to estimate the mass of the SARCS objects .
Among 126 candidates , we obtain a weak lensing detection ( at the 1 \sigma level ) for 89 objects with velocity dispersions of the Singular Isothermal Sphere mass model ( SIS ) ranging from \sigma _ { SIS } \sim 350 \mathrm { km s ^ { -1 } } to \sim 1000 \mathrm { km s ^ { -1 } } with an average value of \sigma _ { SIS } \sim 600 \mathrm { 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 ( M _ { i } < -21 ) , we derive the optical properties of the SARCS candidates .
We obtain typical richnesses of N \sim 5 - 15 galaxies and optical luminosities of L \sim 0.5 - 1.5 \times 10 ^ { 12 } \mathrm { L _ { \odot } } ( within a radius of 0.5 Mpc ) .
We use these galaxies to compute luminosity density maps , from which a morphological classification reveals that a large fraction of the sample ( \sim 45 \% ) are groups with a complex light distribution , either elliptical or multimodal , suggesting that these objects are dynamically young structures .
We finally combine the lensing and optical analyses to draw a sample of 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 \sim 25 \% in \sigma _ { SIS } at a given richness or luminosity , making these scaling laws interesting mass proxies .