THE CFHTLS--STRONG LENSING LEGACY SURVEY (SL2S): INVESTIGATING THE GROUP-SCALE LENSES WITH THE SARCS SAMPLE.

We present the Strong Lensing Legacy Survey-ARCS (SARCS) sample compiled from the final T0006 data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) covering a total non-overlapping area of 159 deg². We adopt a semi-automatic method to find gravitational arcs in the survey that makes use of an arc-finding algorithm. The candidate list is pruned by visual inspection and ranking to form the final SARCS sample. This list also includes some serendipitously discovered lens candidates which the automated algorithm did not detect. The SARCS sample consists of 127 lens candidates which span arc radii ~2"-18" within the unmasked area of ~150 deg². Within the sample, 54 systems are promising lenses among which, we find 12 giant arcs (length-to-width ratio ≥8). We also find two radial arc candidates in SL2SJ141447+544704. From our sample, we detect a systematic alignment of the giant arcs with the major axis of the baryonic component of the putative lens in concordance with previous studies. This alignment is also observed for all arcs in the sample and does not vary significantly with increasing arc radius. The mean values of the photometric redshift distributions of lenses corresponding to the giant arcs and all arcs sample are at z ~ 0.6. Owing to the large area and depth of the CFHTLS, we find the largest sample of lenses probing mass scales that are intermediate to cluster and galaxy lenses for the first time. We compare the observed image separation distribution (ISD) of our arcs with theoretical models. A two-component density profile for the lenses which accounts for both the central galaxy and the dark matter component is required by the data to explain the observed ISD. Unfortunately, current levels of uncertainties and degeneracies accommodate models both with and without adiabatic contraction. We also show the effects of changing parameters of the model that predict the ISD and that a larger lens sample might constrain relations such as the concentration-mass relation, mass-luminosity relation, and the faint-end slope of the luminosity function. [ABSTRACT FROM AUTHOR]