1. Bernard Fort The Strong Lensing Legacy Survey (SL2S) ESO Santiago November 22, 2006 UPMC/CNRS

2. SL2S project Extract and study a large sample of strong gravitational lenses from the CFHTLS wide field survey > 300, possibly 1000 with a lens redshift up to z =1:

3. Institut d’astrophysique de Paris (France) C. Alard, B. Fort, Y. Mellier, Hong Tu (Shangaii NU), J-F Sygnet, Laboratoire d’Astrophysique de Tarbes-Toulouse (France) R. Cabanac, G. Soucail, E. Belsole (Cambridge UK), R. Pelo Laboratoire d’astrophysique de Marseille (France) J.-P. Kneib, E. Julo (ESO), L. Tasca, O. le Fevre UC Santa Barbara (USA) R. Blandford, P. Marshall, R. Gavazzi,.. University de Victoria (Canada) D.Crampton (HIA), K.. Thanjavur (UVic), J. Willis (UVic) Durham University (G-B) M. Swimbank Scientific collaboration

4. CFHT Legacy Survey: a big reservoir of strong lenses Automated procedure to search lenses - arcs in groups and (distant) clusters - gravitational rings SL2S scientific goals Future Outline of the presentation

5. CFHTLS/Deep field 170 deg2 (U, G, R, I, Z), I=24.5: 3.8 millions of galaxies

6. Lensing in cosmology Newtonian gravitational potential Cosmology Cosmology geometry Newtonian potential image magnification

7. For galaxy (QS0) - galaxy lenses (gravitational rings) - big Elliptical represents 2/3 of the lenses - Optical depth ~ 10 -3 Multiple QSOs or arcs around galaxies - QSO: Cosmic Lens All-Sky Survey 12/5000 distant radiosources are lensed by a foreground (E) galaxy (Browne et al 2002) - Galaxy:20 lensed Lyman-α background galaxies for 20,000 massive, E / bulge-dominated galaxies with z>0.4,R 2.2 (APM survey: Willis et al, 2000)

8. Giant arcs in cluster of galaxies RCS giant arcs sample from Gladders et al 2005. Some arcs have Einstein radius up to 50 " (A0024, RCS 0224)

9. Comoving number density of DM halos from Mo & White 2002 cluster, Re ~ 7-20" group Re ~ 3-7" galaxy, Re ~ 1-3" Multiple QSOs/Rings Luminous X-clusters ? Number of DM halos

10. predicted n / 1 sq° Rings -> 10-20 Groups -> 1-2 Clusters -> 0.4 expected CFHTLS Rings > 1000 Groups >100 Clusters > 50 SHMO > 300 Others ? SL2S prediction and detection numbers ? From Oguri 's simulations 2005 How to find rings and arc groups?   observations

11. SIS mass distribution:  ~ 1-3” for a lens galaxy  ~ 10-50” for a cluster of galaxies Can we find intermediate mass lenses ? (3’’<  < 7’’) ? M ~ 3-30 10 12 Mo

12. (from Mellier 2005). Visual detection of giant arcs in CFHTLS

13. Automated detection procedures Arcfinder (Alard 2006) Ringfinder (Gavazzi et al 2006

14. Physical nature of arcs arc thickness ~ seeing search a local elongation with w=seeing 2.5 seing~14 pixel

15. Arcs detector 2.M 2.M px x y x o,y o 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

16. with a typical CFHTLS arc candidate E(x,y) map Detection example From Alard 2006

17. A selected sample of SL2S lenses (10/46 T002 ) CFHTLS/HST SL2S/COSMOS 5921+638 Ringfinder fails for rings with Re<2.7 ’’

18. Preliminary results with CFHTLS ~ 0.65 release T002 release T003 groups distant clusters from Cabanac et al. 2006 ~ 30°°

19. Parametric modeling with lenstool SL2SJ085446-012137

21. HST modeling of SL2SJ085446-012137 But arc redshift ? Bright Galaxy {0,0} Main potential  x= -0.098’’+/- 0.05  y= -0.522’’+/-0.08 Second galaxy produces 2 extra images splitting 7 images configuration

22. First HST follow-up November 2006

23. Main fields of investigations Structure of halos in groups and distant clusters for comparison with simulations: - center of DM halos relatively to the center of brightest central galaxies, nature of fossile groups - relative mass and light ratio and evolution with zl - SL+WL determination of C 200 = R 200 /rs for a large mass spectrum from G to clusters as a function of z l - detection of triaxial halos, study of sub-halos (Rcut), -2D spectroscopy of very distant magnified galaxies and search for galaxies at z>6

24. «Arcfinder» is not efficient for Re > 2.5-3’’ but we also want to find the most numerous population of distant gravitational rings hidden in the CFHTLS ? « Ringfinder»

25. Sloan Lens ACS Survey (SLACS) Bolton 2004, Treu 2005, Koopmann 2005 Searching composite spectra for a signature of two aligned galaxies ACS images

26. Coupling lensing and stellar dynamics Lens modelling give the mass at r Einstein and     DM Stars see the potential for r < r eff Jeans equation  M * / L  v anisotropy  =  (M * / L, , v anisotropy    spectro observation (~ potential slope  from Koopmann & Treu 2005

27. SLACS Lensing -> recovers the Ellipticals fundamental plane For isolated E (external shear perturbation < 0.035) = 1.01 +/- 0.065 rms  (r) ~ r - 2.01 +/- 0.03 near Einstein Radius (~Flat Rot.Curve) PA and ellipticity of light and DM trace each other ( M * ~75%) No evolution ( ~0.2)

28. a HDF source arc(let)s How to recognize a ring a HDF Elliptical seeing = 0.8 arcsec circular source CFHTLS arc(let)s circular lens HST ? ? True G-Ring but spiral like! Simulations of rings around E-lenses

29. Finding CFHTLS ring candidates Detection: Based on color information (often 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. ~10-20 candidates/deg 2 (Raphael Gavazzi 2006)

30. SL2S 02 25 11- 04 54 33

31. A Sample of ringfinder candidates in D1 A spectroscopic follow-up of the arcs is necessary to confirm the candidates

32. Test with the CFHTLS-COSMOS field Gavazzi June 2006 4117 (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

33. A SL2S cosmological tests with rings ? Hypothesis: Treu's results =1. +/- 0.065 r(r) ~ r - 2.01+/-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 ) Log r ReRe Lens modeling VLT spectroscopy

34. First Year results (~1/5 of the CFHTLS field ) -47 multiple arc(let) systems in groups and distant clusters were discovered and are being observed with the HST - > 100 gravitational ring candidates tbc! - many singly highly magnified lens events with m>3-5) - Several multi-plan lenses and a few possible dark rings

35. Several other large (cosmic shear) surveys are planned Deep lens survey 28 deg2 on going RCS2 1000 deg2 started Kids-VST/OmegaCAM 1000 deg2 VISTA-IR galaxy survey near IR rings ? LSST 10 000 deg 2 2008 Pan-StARRS 10 000 deg 2 2012 SNAP Space survey 1000 deg 2 ? >2011 Futur

36. Extending the technique to near IR survey Systematic scan of high magnification regions for Lyman-a emission at z~5-8. Recently z~6 galaxies found this way. Small primeval halos: 10 6 M o - first stars? Dynamical studies with 2D spectroscopy of brightest distant arcs to get rotation curves (Karun Thanjavur, David Crampton, Jon Willis)

37. SNAP  Joint Dark Energy Mission: NASA (75%) & DOE (25%) launch 2014-2015 6 years survey: super novae and weak lensing SNAP: 2m telescope, instrument FOV 1 deg 2 Imaging / spectro. one deep field (15 deg 2 ), one large field (~300 deg 2 ?) ~ 1Billlion $  DUNE (Dark Universe Explorer): similar survey but 1.2-1.5m telescope and imaging only instrument FOV 1 deg 2 ~ 300 M€ Prediction snap n ~ 4000 and 14000 strong lenses

38. Conclusions SL2S will be the largest SL database available for the next 5 years, possibly 1000 SL, if we have spectroscopic follow-up. - SL2S will extend the lensing studies of galaxy mass evolution at large z and groups (a new classe of SGL) - Numerous rings and arc systems for a large mass spectrum allow statistical tests (cf Oguri 2005). -offer the possibility to observed magnified galaxies at z > 6 - SL2S is a benchmark for the preparation of SL analyses with SNAP or DUNE-like survey.

43. 10 – 30 % of all very distant sources (z>4) are magnified with  >10 (Keeton’s prediction 04 astro-ph/0405143) CFHTLS highly magnified drop-out galaxies >3>3 NWF SIE From Omont et al. 2005 Singly Highly-Magnified Event

44. Multiple arc system from cosmic string HST field same HST field + string loop

45. Finding arcs within clusters members Typical cases in A1689 Note the cluster shear effect: testing the potential slope

46. SDSS survey for giant arcs Sloan 8000 deg2 images to detect clusters using the red sequence technique 0.1<z<0.6 - follow_up with UH88 gives 240 clusters - 141 with sub-arcsecond seeing - 16 with giant arcs and 9 with shortest arcs Hennawi et al 2006 Inner arc

47. Arc systems with an elliptical lens. Radial arc Cusp arc Einstein Cross Fold arc Singly magnified image of a distant galaxy From Kneib et al 1993

48. Cosmological parameters D ls /D os Distribution halos X-section + conection Light -> total mass L * ->  * ->  L Evolution (z) Parametrization -> An overlook on lensing probability (Ofek, Rix & Maoz 2003) Optical depth per unit redshift  ( , z s ) Merging rate Luminosity, M evolution,..

49. Prob[z lense ] variations with various parameters z source  m,  or wo,w1;.. mass evolution varying   (Ofek, Rix & Maoz 2003) Merger evolution

50. More information http://www.cfht.hawaii.ed u/~cabanac/SL2S/ The SL2S I: Cabanac et al. 2006

51. French/ESA programs

52. Sloan Lens ACS Survey (SLACS) Bolton 2004, Treu 2005, Koopmans 2005) Sample ~ 120 candidates with ongoing HST snap survey

53. OII 3127Å Zs=1.32 4000 Å ZL=0.63 A three-step procedure to search more rings 2- spectroscopy (VIMOS) Goal find n ring ~ 10/ ° If successful SL2S => n ring ~ 1000 ! 1- CFHTLS imagery to select possible SL n candidates < 200 /° 3- HST snap >80% confirmation rate

54. OLS Multiple images formation Convergence + shear + Fermat principle gravitational lense effects

55. 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 (0.2-0.8) 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

56. Schechter distribution L(z)/L*(z) of SIS halos Faber-Jackson (Tully-Fisher) law Observational relation (SLOAN)  DM = f(  * ) dt/dz = n(  E, z) (1 + z) 3 XS c.dt/dz + + Comoving number n NFW (z) (Mo and White 2000) + Estimation of the optical depth Treu et al. 2006 Elliptical ->  L =  * Analytical method or simulation

57. Fraction of multiply lensed QSOs ~2.10 -3 JVAS + Cosmic Lens All-Sky Survey 12/5000 distant radiosources are lensed by a foreground (E) galaxy (astro_ph/0211069, Browne et al; Chae 2002, 2004, Chen et al, 2004, ApJ 607, L71) ~ 0.4 ~ 4 Gpc n o = 0.5 10 -2 Mpc -3, ~ 1 arcsec for SIS:   ~ n o Ds ~ 10 -3

58. Arc modelling with pixel deprojection HST/ACS : a modelling of a D2/CFHTLS arc by Gavazzi et al. 2005 b/a b 0.7 5"4" 0.8

59. Arcs geometry depends on the projection matrix Projected potential derivatives * Dol. Dls / Dos