Christophe Alard (IAP), Rémi Cabanac (CFHT), Bernard Fort (IAP), Jean-Paul Kneib (LAS), Raphael Gavazzi (Santa-Barbara), Jean-François Sygnet (IAP), Mireille Dantel-Fort (OPM-Terapix), G. Soucail, (OMP), Yannick Mellier (IAP), Phil. Marshall (UC), Sherry Suyu (Caltech), Roger Blandford (Stanford), Olivier Le Fèvre (LAS), David Valls-Gabaud (OPM).. CFHT- SL2S Strong Lensing Legacy Survey SF2A- July.26, 2006 Rémi Cabanac (CFHT)

Galaxy lenses from serendipity… APM survey: Willis et al, lensed Lyman-α background galaxies within 2000 massive, E / bulge-dominated galaxies with Z > 0.4, R 2.2 RCS1 giant arc sample (Gladders et al 2005) Only in massive (X-ray) clusters. Giant arcs have Einstein radius 8" <Re < 50 " (e.g. A1689, RCS 0224)

CFHTLS-Wide (170sq°) is a big reservoir of strong lenses: expected number with nominal limiting magnitude and seeing < 0.85 arcsec Rings ~ 1500 Groups ~ 100 Clusters ~ 50 SHMO (  >3) > 300 Others ? SL2S predictions ? From Oguri 's simulations 2005 automated softwares ~ How to find them?

Develop automated procedure to search the lenses Make HST imagery and VLT spectroscopy follow-up Model and analyse the CFHTLS strong lens sample - mass distribution in groups - lensing study of distant galaxy up to z ~ 1 Prepare the future (SNAP, DUNE) The SL2S project

An overview of the CFHTLS-SL2S project

Arcs detectors M M px x y x o,y o Alard's local estimator  I (x o + x, y o ) dx 2.M. Max [-M<x<M] [  I (x o + x, y o +y) dy] E(x o, y o ) = Arc reconstruction by a small scale estimator of a local elongation (seeing width) of light distribution scanning aperture M x M pixel unit (M ~7) unit, optimal mexican hat filtering (x,y) local axis aligned on second E( x o,y o ) moments of light distribution map

A typical CFHTLS arc candidate corresponding E(x,y) map Detection example From Alard 2006

CFHTLS-SL2S Terapix Release T0002 groups

Better modeling with HST images (HST C15 SL2S SNAP proposal is accepted: 50 orbits) Modeling of groups: halo and sub-halos mass distribution, halo occupation number, X-ray connection, evolution M/L,..

From SLACS to CFHTLS rings Finding rings in the CFHTLS-wide is a great challenge (seeing effect), but if successful SL2S => n ring ~ 1500 ! Sciences: Evolution lens parameters with z (profile slope, total mass, M/L,..) at larger redshift ( ) than the SLOAN survey ( ~0.2) Sloan Lens ACS Survey (SLACS) Bolton 2004, Treu 2005, Koopmans 2005 Study ~ 20/120 candidates with ongoing HST snap survey

Finding CFHTLS ring candidates (Raphael Gavazzi 2006) Detection: Based on color information. Rings are blue and lenses are red(early-type galaxies)! Method: Fit a B-  R profile consistent with the lens color. Identify a sharp elongated blue excess at 0.8<r<2.5'' above the (B-  R) noise. ~1-20 candidates/deg 2 to be confirmed spectroscopically (we only expect a few!)

Result in the CFHTLS-COSMOS field Gavazzi June (E/So or Sa) galaxies with 18 <I < 22 are selected. 783 with a small residual blue light in the annulus. 72 candidates above the reference threshold. Indeed all the blue cosmos rings are recovered (but obviously not the red ones). Near future: optimisation + (R-Z, etc.) tests red ring

SLACS Lensing -> recovers the Ellipticals fundamental plane For isolated E (external shear perturbation < 0.035) = / rms  (r) ~ r / near Einstein Radius (~Flat Rot.Curve) PA and ellipticity of light and DM trace each other ( M * ~75%) No evolution ( ~0.2)

A SL2S cosmological tests with rings ? Hypothesis: Treu's results =1. +/ r(r) ~ r /-0.03 at Re ~ Flat Rot. Curve (DM light-conspiracy) R e /  L = D ol D ls /D os R e /  * = G ( , or w 0,w 1 ) Gavazzi 2006 Log R Log r ReRe Lens modeling VLT spectroscopy

The 300 sq ° Weak Lensing field  lens and the deep SN survey (15 sq°) => 4900 lense events (from Marshall, Blandford et al ) The SNAP or Deep Universe Probe

Conclusions - SL2S, extrated from CFHTLS, will be the largest SL database available for the next 5 years ~/> 1000 SL (still improved automated procedures). - SL2S will significantly extend the current lensing studies in the fields of galaxy evolution, uncovering the study of intermediate mass halos of groups. - Gravitational telescope (many magnified high z galaxies) - Numerous rings will allow statistical analysis. - SL2S constitutes a benchmark for the preparation of SL analyses with SNAP or DUNE-like survey.

Example of data: 0047 at z= hrs integration; velocity dispersion profile to ~5 %

Method: dynamical model Two spherical components –Luminous component: Hernquist/Jaffe mass distribution –Dark matter profile: generalized NFW profile, with inner slope - , outer slope -3, break radius R b –Osipkov-Merritt parametrization of the anisotropy, or constant anisotropy. Spherical Jeans equation

Results. I: luminous and dark matter in high-z E/S0s Constant M/L ruled out; dark matter halos detected!! Isotropic or mildly radial orbits Approximately flat rotation curve Result of (incomplete) violent relaxation?