Bernard Fort (IAP)

SL2S project team

Remi Cabanac (coord. CFHTLS), Christophe Alard, Mireille Dantel-Fort (Obs. de Paris/Terapix), Jean-Paul Kneib (Marseille, HST follow-up), Jean-François Sygnet (IAP), Raphael Gavazzi (PostDoc)

CFHTLS-Strong Lensing Legacy Survey

CFHT/ Feb.15,2006

David Valls-Gabaud (CFHT), Olivier Le Fevre (Marseille), Genevieve Soucail (Toulouse), Roser Pello (Toulouse),Yannick Mellier (Terapix), Cecile Faure (Marseille),

Philip Marshall, Sherry Suyu, Roger Blandford (HST C15 SL2S SNAP Proposal)

Karun Thanjavur, David Crampton, Jon Willis,

(Tommaso Treu, Leon Koopman, ...tbd)

Collaborations

• Strong lensing optics• CFHTLS as a reservoir of strong lenses• Automated procedure to search lenses• Finding more rings• SL2S scientific goals• Conclusions

Outline of the presentation

The thin lens equation

• the generic lensing configuration

• the thin lens equation

• Lensing is a pure geometrical effect and is achromatic

Newtonian gravitational potentialCosmology

O L S

Multiple images formation

c = c2 Ds

4 G Dd Dds

0.35 g cm-2 for D~1 Gpc

Convergence+ shear

Einstein radius

• For a point mass: Einstein radius

• Isothermal sphere mass distribution:

~ 1-3” for a lens galaxy

~ 10-30” for a cluster of galaxies

spherical lense M(RE) does not depend on the mass profile

Images formation for a strong lens

Multiple-images configurations for a non-singular elliptical lens.

Distorted images with typical shapes (tangential and/or radial distorsion)

Radial arc

Cusp arc

Einstein Cross Fold arc

Single image

Gravitational images in MS2137-23

A4

A1

A2

A3B1-B2

B3

Lens types

• galaxy (QSO)-galaxy strong lensing (mostly rings)

• multiple arc(let) systems in groups and clusters

• Singly highly magnified lens events (SHME with >3-5)

• Possible unexpected lens events (multi-plan events, dark lenses, cosmic strings,..)

Fraction of multiply lensed QSOs ~2.10-3

JVAS + Cosmic Lens All-Sky Survey 12/5000 distant radiosourcesare lensed by a foreground (E) galaxy(astro_ph/0211069, Browne et al; Chae 2002, 2004 , Chen et al, 2004, ApJ 607, L71)

<zlens> ~ 0.4 <Dsource> ~ 4 Gpc

no = 0.5 10-2 Mpc-3, < REinstein> ~ 1 arcsec

for SIS:

~ no < (REinstein)2 > Ds ~ 10-3

RCS1 giant arc sample from Gladders et al 2005

Some arcs have Einstein radius up to 50 "

A1689, RCS 0224

Specific X-ray Cluster surveys

A MDF sample of galaxy- galaxy lenses: big Elliptical represents 2/3 of the lenses (Ranatunga 2003)

Arcs around galaxies

20 lensed Lyman-α background

galaxies for 2000 massive, E / bulge-dominated galaxies

with z>0.4,R<20,B-R>2.2

(APM survey: Willis et al, 2000)

Sloan Lens ACS Survey (SLACS)Bolton 2004, Treu 2005, Koopmans 2005)

Study ~ 15/120 candidates with ongoing HST snap survey

SLACS

Lensing -> recovers Ellipticals fundamental plane <L/*> =1.01 +/- 0.065 rmsSIE(r) ~ r-2.01 +/- 0.03 at Einstein Radius (~Flat Rot.Curve) external shear perturbation < 0.035 Study of Mgal (z), M/L but <ZL>~0.2

Comoving number density of DM halosfrom Mo & White 2002

cluster, Re ~ 7-20"

group Re ~ 3-7"

galaxy, Re ~ 1-3"

Multiple QSOs/Rings

Luminous X-clusters

?

CFHTLS as reservoir of strong lenses

Schechter distribution L(z)/L*(z)of SIS halos

Faber-Jackson (Tully-Fisher) law

Observational relation (SLOAN) DM = f(*)

d/dz = n(E, z) (1+z)3 XS c.dt/dz

+

+

<cross-section XSNFW (z)>

Comoving number n NFW (z)(Mo and White 2000)

+

Estimation of the optical depth

Treu et al. 2006Elliptical -> L = *

Analytical method simulations

predicted n / 1 sq°

Rings -> 10-20

Groups -> 1-2

Clusters -> 0.4

expected SL2S

Rings > 1000Groups >100Clusters > 50SHMO > 300 Others ?

SL2S prediction and detection numbers

?

From Oguri 's simulations 2005

How to find

rings?

Automated detection procedures

Still in developement

Rings (Sygnet et al, Cabanac, ..)

Arcs/ring (Alard) -> HST proposal

Multiple arclets (Fort-Dantel,..)

a HDF source

arc(let)s

Simulations of rings around E-lenses

a HDF Elliptical seeing = 0.8 arcsec

circular source CFHTLS

arc(let)s

circular lens

HST

?

?(spiral like!)

Software rings (Sygnet 2005)

MappingPixel flux(I,G)

Pxf I

Pxf G

Pattern recognition

Mapping sub-mage I-G, Z-U, ..., any combinations

Visual detectionOn a color image

Software multiplets (Dantel-Fort 2005)

Eliminate stars & select multiplets(n, quad, triplet,..)

with same color (U-G,..)

Select arclet sytemsfrom generic properties

of lens systems

Test models and flag candidates

Sextractor catalogsU,G,R,I,Z

arclets geometryx, y, , dij, ..

seeing

Mag., deflector

radial pair

parallel pair

saddle pair

tripletquadruplet

circular pair

A selection of generic arc(let) systems

2-Automatic pattern recognition of (almost) connected successive (faint) arclets (width = seeing, length~ 2.5 seeing) on constant curvature lines. Eyeball final selection

Software "arc" (Alard 2005)

Simple and very efficient -> 50 candidates / 45°

...> ......

1-Attenuation of galaxy halos

CFHTLS-SL2S preliminary results

T002 release

45 °/170° already analysed

Detection software not yet fully optimized

50 arcs mostly with Re>2"(HST snap proposal Cycle 15)

Most rings tbc with spectroscopy for SL2S 0.2<zL<1 !

A selected sample of SL2S lenses (11/48)

CFHTLS/HST

SL2S/COSMOS 5921+638

0 0.2 0.4 0.6 0.8

1

2

3

4

5

6

7

Comparison zL SLACS-SL2S

SLACS SL2S (color redshifts)ZL SLACS limit

0 2.5 5 7.5 10 12.5 15 17.5

5

10

15

20

25

30

Distribution of SL2S1 arc radii

arcsec.

QSOs

SL2S1

Many detections for 3"< <6"

Cluster lenses

Galaxy lenses

Oguri 2005

n poor detection for < 2"

OII 3127ÅZs=1.32

4000 ÅZL=0.63

A three-step procedure to search more rings

2- spectroscopy (VIMOS)Goal find nring ~ 10/°

If successful SL2S => nring ~ 1000 !

1- CFHTLS imageryto select possible SL

ncandidates < 200 /°

3- HST snap>80%

confirmation rate

Lens potential: number, ellipticity, mass profile and evolution of DM halos, evolution with z (high z elliptical lenses, correlation X-survey, arc statistics); modelling of individual lens (group)

Statistical cosmological tests with rings is a challenging but exciting topic.

Lens as natural telescope: study of very high-z galaxies, statistical study of the magnification bias (Keeton 2005, Almaini et al. 2005 astro-ph/0501169)

SL2S scientific goals

SL2S 085446-012137

Parametric modelling of an intermediate mass lense

Zl = 0.3 Zs=1 ?Rc=1.07 kpc 471km/se = 0.31 PA=40° Model with several potentials=> light ~ traces mass

Zl = 0.3 Zs=1 ?Rc=1.07 kpc 530 km/se = 0.58 PA= 20°Model with a single potential

Snap HST images with a higher resolution are necessary

Arc modelling with pixel deprojection

HST/ACS : a modelling of a Cosmos arc Gavazzi et al. 2005

b/a

b

0.7

5"4"

0.8

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

NWFSIE

Omont et al. 2005

Singly Highly-Magnified Event

SL2S lens studies

• Modelling of lenses

main target: groups (halo, sub-halos) with their X-ray connection

• Evolution of (ring) lens parameters with z (profile slope, total mass, M/L, concentration parameter) for <zl> at larger redshift (0.2-0.8) than the SLOAN survey (<z>~0.2)

Cosmological parameters Dls/Dos

Distribution halos

X-section + conectionLight -> total mass L*-> *->L

Evolution (z)Parametrization ->

An overlook on lensing probability(Ofek, Rix & Maoz 2003)

Optical depth per unit redshift (, zs)

Merging rateLuminosity, M evolution,..

Prob[zlense] variations with various parameters

zsource

m ,

wo,w1;..

possible tests?

mass evolution

varying

(Ofek, Rix & Maoz 2003) Merger evolution

A SL2S cosmological tests with 300 rings ?

Hypothesis: Treu observational results hold at larger z<L/*> =1.01 +/- 0.065 rmsSIE(r) ~ r-2.01 +/- 0.03 at Einstein Radius (~Flat Rot. Curves)External shear perturbation < 0.035

Gavazzi 2006

Gravitational telescope

• Systematic scan of high magnification regions for Lyman-a emission at z~5-10. Recently found z~6 -7 galaxy this way (Pello et al.)!

• Small primeval halos: 106 Mo - first stars?

• Dynamical studies with 2D spectroscopy of brightest arcs (Karun Thanjavur, David Crampton, Jon Willis)

The 300 sq ° Weak Lensing field

=> 15000 lens and

the deep SN survey (15 sq°)

=> 4900 lense events

(from Marshall, Blandford et al. 2004)

The SNAP or Deep Universe Probe SL perspective

DUNE project

1.2 m-class space telescope30 arcmin-1 sq° field of view1 (or eventually 2) filters (I)U, B, V, R, ...Z, K (from ground)Survey size: 10 000 sq°End of feasability study: Dec. 2006Launch: 2011-2012Main target: cosmic shear

up to 100 000 SL !!!

Conclusion

- CFHTLS can give the largest SL database available for the next 5 years ~/> 1000

- need to use improved automated procedures

-will significantly extend the current lensing studies in the fields of galaxy (halo) evolution, uncovering the study of intermediate mass halos (groups)

- can open exciting statistical analysis concerning the distribution an behavior of DM and DE

- is a benchmark for the preparation of SL analyses with SNAP/DUNE

http://www.cfht.hawaii.edu/~cabanac/SL2S/

Now we can say the CFHTLS-SL2Sis a viable project

French/ESA programs

A CFHTLS gallery of giant arcs from Mellier 2005 discovered in the W3 field.

Giant arcs in clusters of galaxies

• Mysterious 'Giant arcs' in A370,Cl2244

– Paczynski suggests lensing– 1987 Fort et al. confirm. Spectroscopy.

• Clusters are more massive than expected

History

Futur SL2S cosmological tests with 300 rings

Hypothesis: Treu observational results hold<sL/s*> =1.01 +/- 0.065 rmsSIE(r) ~ r-2.01 +/- 0.03 at Einstein Radius (FRC)external shear perturbation < 0.035

Gavazzi 2006

A370

SL2S(first 45sq°)QSOs

Groups ?

Distribution of SL2S arc radii