Bernard Fort (IAP)

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CFHTLS-Strong Lensing Legacy Survey

• 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)

CFHT/ Feb.15,2006
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Collaborations

• 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)

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Outline of the presentation

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

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The thin lens equation

• the generic lensing configuration
• the thin lens equation
• Lensing is a pure geometrical effect and is
  achromatic

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Multiple images formation
Convergence shear
O
L
S
?c c2 Ds
4 ? G Dd Dds
0.35 g cm-2 for D1 Gpc
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Einstein radius

• For a point mass Einstein radius
• Isothermal sphere mass distribution

a 1-3 for a lens galaxy
a 10-30 for a cluster of galaxies
spherical lense M(RE) does not depend on the
mass profile
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Images formation for a strong lens
Single image
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
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Gravitational images in MS2137-23
A4
B3
A3
B1-B2
A1
A2
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Lens types

• galaxy (QSO)-galaxy strong lensing (mostly rings)
  
• multiple arc(let) systems in groups and clusters
• Singly highly magnified lens events (SHME with
  mgt3-5)
• Possible unexpected lens events
• (multi-plan events, dark lenses, cosmic
  strings,..)

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Fraction of multiply lensed QSOs 2.10-3
ltzlensgt 0.4 ltDsourcegt 4 Gpc no
0.5 10-2 Mpc-3, lt REinsteingt 1 arcsec for
SIS t no lt p (REinstein)2 gt Ds
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)

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RCS1 giant arc sample from Gladders et al 2005
Specific X-ray Cluster surveys
Some arcs have Einstein radius up to 50
" A1689, RCS 0224
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Arcs around galaxies
20 lensed Lyman-a background galaxies for 2000
massive, E / bulge-dominated galaxies with
zgt0.4,Rlt20,B-Rgt2.2 (APM survey Willis et al,
2000)
A MDF sample of galaxy- galaxy lenses big
Elliptical represents 2/3 of the lenses
(Ranatunga 2003)
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Sloan Lens ACS Survey (SLACS)
Bolton 2004, Treu 2005, Koopmans 2005) Study
15/120 candidates with ongoing HST snap survey
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SLACS
Lensing -gt recovers Ellipticals fundamental
plane ltsL/sgt 1.01 /- 0.065 rms SSIE(r)
r-2.01 /- 0.03 at Einstein Radius (Flat
Rot.Curve) external shear perturbation lt 0.035
Study of Mgal (z), M/L but ltZLgt0.2
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Comoving number density of DM halosfrom Mo
White 2002
CFHTLS as reservoir of strong lenses
Multiple QSOs/Rings
galaxy, Re 1-3"
?
group Re 3-7"
cluster, Re 7-20"
Luminous X-clusters
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Estimation of the optical depth
Analytical method simulations
Schechter distribution L(z)/L(z) of SIS halos
Comoving number n NFW (z) (Mo and White 2000)


Faber-Jackson (Tully-Fisher) law
ltcross-section XSNFW (z)gt

Observational relation (SLOAN) sDM f(s)
Treu et al. 2006 Elliptical -gt sL s
dt/dz n(qE, z) (1z)3 XS c.dt/dz
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SL2S prediction and detection numbers
predicted n / 1 sq Rings -gt
10-20 Groups -gt 1-2 Clusters -gt 0.4
?
How to find rings?
expected SL2S Rings gt 1000 Groups
gt100 Clusters gt 50 SHMO gt
300 Others ?
From Oguri 's simulations 2005
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Automated detection procedures
Still in developement Rings (Sygnet et al,
Cabanac, ..) Arcs/ring (Alard) -gt HST
proposal Multiple arclets (Fort-Dantel,..)
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Simulations of rings around E-lenses
CFHTLS
HST
circular source
circular lens
?
arc(let)s
arc(let)s
(spiral like!)
?
a HDF source
a HDF Elliptical
seeing 0.8 arcsec
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Software rings (Sygnet 2005)
Pxf I
Pattern recognition
Pxf G
Visual detection On a color image
Mapping Pixel flux(I,G)
Mapping sub-mage I-G, Z-U, ..., any combinations
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Software multiplets (Dantel-Fort 2005)
Eliminate stars select multiplets(n, quad,
triplet,..) with same color (U-G,..)
Sextractor catalogs U,G,R,I,Z
arclets geometry x, y, e, j, dij, .. seeing
Select arclet sytems from generic properties of
lens systems
Mag., S, .. deflector
Test models and flag candidates
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A selection of generic arc(let) systems
radial pair
parallel pair
saddle pair
circular pair
quadruplet
triplet
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Software "arc" (Alard 2005)
Simple and very efficient -gt 50 candidates / 45
1-Attenuation of galaxy halos
2-Automatic pattern recognition of (almost)
connected successive (faint) arclets (width
seeing, length 2.5 seeing) on constant curvature
lines. Eyeball final selection
...gt
......
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CFHTLS-SL2S preliminary results
T002 release 45 /170 already
analysed Detection software not yet fully
optimized 50 arcs mostly with Regt2" (HST snap
proposal Cycle 15) Most rings tbc with
spectroscopy for SL2S 0.2ltzLlt1 !
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A selected sample of SL2S lenses (11/48)
SL2S/COSMOS 5921638
CFHTLS/HST
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Comparison zL SLACS-SL2S
SLACS
SL2S (color redshifts)
ZL SLACS limit
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Distribution of SL2S1 arc radii
n
poor detection for q lt 2"
QSOs
Galaxy lenses
Oguri 2005
Many detections for 3"ltq lt6"
SL2S1
Cluster lenses
arcsec.
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A three-step procedure to search more rings
1- CFHTLS imagery to select possible SL
ncandidates lt 200 /
2- spectroscopy (VIMOS) Goal find nring 10/
OII 3127Å Zs1.32
4000 Å ZL0.63
3- HST snap gt80 confirmation rate
If successful SL2S gt nring 1000 !
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SL2S scientific goals
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)
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Parametric modelling of an intermediate mass lense
SL2S 085446-012137
Zl 0.3 Zs1 ? Rc1.07 kpc 471km/s e 0.31
PA40 Model with several potentials gt light
traces mass
Zl 0.3 Zs1 ? Rc1.07 kpc 530 km/s e 0.58
PA 20 Model with a single potential
Snap HST images with a higher resolution are
necessary
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Arc modelling with pixel deprojection
b/a
0.8
0.7
b
HST/ACS a modelling of a Cosmos arc Gavazzi
et al. 2005
5"
4"
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CFHTLS highly magnified drop-out galaxies
Singly Highly-Magnified Event
SIE
NWF
Omont et al. 2005
10 30 of all very distant sources (zgt4) are
magnified with mgt10 (Keetons prediction 04
astro-ph/0405143)
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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 ltzlgt at larger redshift (0.2-0.8)
  than the SLOAN survey (ltzgt0.2)

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An overlook on lensing probability(Ofek, Rix
Maoz 2003)
Distribution halos
X-section conection Light -gt total mass
L-gt s-gtsL
Cosmological parameters Dls/Dos
Merging rate Luminosity, M evolution,..
Evolution (z) Parametrization -gt
Optical depth per unit redshift t(q, zs)
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Probzlense variations with various parameters
varying q

zsource
W m , Wl wo,w1.. possible tests?
Merger evolution
mass evolution
(Ofek, Rix Maoz 2003)
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A SL2S cosmological tests with 300 rings ?
Hypothesis Treu observational results hold at
larger z ltsL/sgt 1.01 /- 0.065 rms SSIE(r)
r-2.01 /- 0.03 at Einstein Radius (Flat Rot.
Curves) External shear perturbation lt 0.035
Gavazzi 2006
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Gravitational telescope

• Systematic scan of high magnification regions for
  Lyman-a emission at z5-10. Recently found z6 -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)

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The SNAP or Deep Universe Probe SL perspective
The 300 sq Weak Lensing field gt 15000 lens
and the deep SN survey (15 sq) gt 4900
lense events (from Marshall, Blandford et al.
2004)
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DUNE project
1.2 m-class space telescope 30 arcmin-1 sq field
of view 1 (or eventually 2) filters (I) U, B, V,
R, ...Z, K (from ground) Survey size 10 000
sq End of feasability study Dec. 2006 Launch
2011-2012 Main target cosmic shear
up to 100 000 SL !!!
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Conclusion

• - CFHTLS can give the largest SL database
• available for the next 5 years /gt 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
  

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Now we can say the CFHTLS-SL2S is a viable project
http//www.cfht.hawaii.edu/cabanac/SL2S/
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French/ESA programs
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Giant arcs in clusters of galaxies
A CFHTLS gallery of giant arcs from Mellier 2005
discovered in the W3 field.
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History

• Mysterious 'Giant arcs' in A370,Cl2244
• Paczynski suggests lensing
• 1987 Fort et al. confirm. Spectroscopy.
• Clusters are more massive than expected

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Futur SL2S cosmological tests with 300 rings
Hypothesis Treu observational results
hold ltsL/sgt 1.01 /- 0.065 rms SSIE(r) r-2.01
/- 0.03 at Einstein Radius (FRC) external shear
perturbation lt 0.035
Gavazzi 2006
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A370
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Distribution of SL2S arc radii
SL2S(first 45sq)
QSOs
Groups ?