Bernard Fort The Strong Lensing Legacy Survey (SL2S) ESO Santiago November 22, 2006 UPMC/CNRS.
-
Upload
monica-daniels -
Category
Documents
-
view
217 -
download
0
Transcript of Bernard Fort The Strong Lensing Legacy Survey (SL2S) ESO Santiago November 22, 2006 UPMC/CNRS.
Bernard Fort
The Strong Lensing Legacy Survey (SL2S)
ESO Santiago November 22, 2006 UPMC/CNRS
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:
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
• 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
CFHTLS/Deep field
170 deg2 (U, G, R, I, Z), I=24.5: 3.8 millions of galaxies
Lensing in cosmology
Newtonian gravitational potentialCosmology Cosmology geometry Newtonian potential
image magnification
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 radiosourcesare 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<20,B-R>2.2(APM survey: Willis et al, 2000)
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)
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
?
Number of DM halos
predicted n / 1 sq°
Rings -> 10-20
Groups -> 1-2
Clusters -> 0.4
expected CFHTLS
Rings > 1000Groups >100Clusters > 50SHMO > 300 Others ?
SL2S prediction and detection numbers
?
From Oguri 's simulations 2005
How to find rings and arc groups?
observations
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 1012 Mo
(from Mellier 2005).
Visual detection of giant arcs in CFHTLS
Automated detection procedures
Arcfinder (Alard 2006)
Ringfinder (Gavazzi et al 2006
Physical nature of arcs
arc thickness ~ seeing
search a local elongation with w=seeing
2.5 seing~14 pixel
Arcs detector
2.M
2.Mpx
xy
xo,yo
local estimator
I(xo + x, yo) dx
2.M . Max [-M<x<M] [ I(xo + x, yo+y) dy]E(xo,yo) =
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(xo,yo) moments of light distribution map
with a typical CFHTLS arc candidate
E(x,y) map
Detection example
From Alard 2006
A selected sample of SL2S lenses (10/46T002)
CFHTLS/HST
SL2S/COSMOS 5921+638
Ringfinder fails for rings with Re<2.7 ’’
Preliminary results with CFHTLS
<zl> ~ 0.65
release T002
release T003
groups distant clusters
from Cabanac et al. 2006~ 30°°
Parametric modeling with lenstool
SL2SJ085446-012137
SL2SJ085446-012137
HST modeling of SL2SJ085446-012137
But arc redshift ?
Bright Galaxy {0,0}Main potential x= -0.098’’+/- 0.05y= -0.522’’+/-0.08
Second galaxy produces 2 extra images splitting 7 images configuration
First HST follow-up November 2006
Main fields of investigationsStructure 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 C200= R200/rs for a large mass spectrum from G to clusters as a function of zl
- detection of triaxial halos, study of sub-halos (Rcut), -2D spectroscopy of very distant magnified galaxies and search for galaxies at z>6
«Arcfinder» is not efficient for Re > 2.5-3’’but
we also wantto find the most numerous
population of distant gravitational rings hidden in the CFHTLS ?
« Ringfinder»
Sloan Lens ACS Survey (SLACS) Bolton 2004, Treu 2005, Koopmann 2005
Searching composite spectra for a signature of two aligned galaxies
ACS images
Coupling lensing and stellar dynamics
Lens modelling give the mass at rEinstein andDM
Stars see the potential for r < reff Jeans equation
M* / Lv anisotropy= (M* / L, , v
anisotropyspectro
observation
(~ potential slope
from Koopmann & Treu 2005
SLACS
Lensing -> recovers the Ellipticals fundamental planeFor isolated E (external shear perturbation < 0.035)
<L/*> = 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 (<10%) of parameters with z (but for SLACS lens galaxies the average redshift is around <ZL>~0.2)
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
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/deg2(Raphael Gavazzi 2006)
SL2S 02 25 11- 04 54 33
A Sample of ringfinder candidates in D1
A spectroscopic follow-up of the arcs is necessary to confirm the candidates
########################################################################## ID RA DEC Re F814w z # #########################################################################
C009 10:00:09.7 02:24:55 2.6 19.3 0.39 C012 10:00:12.6 02:20:15 0.82 18.3 0.39 C013 10:00:13.9 02:22:49 1.7 18.9 0.36 C018 10:00:18.4 02:38:45 1.7 23.2 0.73 C056 10:00:56.7 02:12:26 2.02 18.9 0.42 C148 10:01:48.1 02:23:25 1.48 19.3 0.39 C208 10:02:08.5 02:14:22 1.59 19.88 0.41 C211 10:02:11.2 02:11:39 3.6 21.27 0.91 C216 10:02:16.8 02:29:55 2.1 17.96 0.59 C221 10:02:21.1 02:34:40 1.6 19.2 0.42 C921 09:59:21.7 02:06:38 0.68 18.3 0.44 C929 09:59:29.9 02:13:52 2.4 17.4 0.25
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
red ring
red ring
red ring
A SL2S cosmological tests with rings ?
Hypothesis: Treu's results
<L/*> =1. +/- 0.065
r(r) ~ r - 2.01+/-0.03 at Re ~ Flat Rot. Curve (DM light-conspiracy)
Re/L = Dol Dls /D os
Re/* = G (, or w0,w1)Log r
Re
Lens modeling
VLT spectroscopy
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
Several other large (cosmic shear) surveys are planned
Deep lens survey 28 deg2 on goingRCS2 1000 deg2 startedKids-VST/OmegaCAM 1000 deg2VISTA-IR galaxy survey near IR rings ?
LSST 10 000 deg 2 2008Pan-StARRS 10 000 deg 2 2012SNAP Space survey 1000 deg 2 ? >2011
Futur
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: 106 Mo - first stars?
• Dynamical studies with 2D spectroscopy of brightest distant arcs to get rotation curves (Karun Thanjavur, David Crampton, Jon Willis)
SNAPJoint Dark Energy Mission: NASA (75%) & DOE (25%) launch 2014-2015
6 years survey: super novae and weak lensing SNAP: 2m telescope, instrument FOV 1 deg2
Imaging / spectro. one deep field (15 deg2), one large field (~300 deg2 ?) ~ 1Billlion $
• DUNE (Dark Universe Explorer): similar survey but
1.2-1.5m telescope and imaging only instrument FOV 1 deg2
~ 300 M€
•Prediction snap n ~ 4000 and 14000 strong lenses
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.
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
From Omont et al. 2005
Singly Highly-Magnified Event
Multiple arc system from cosmic string
HST field same HST field + string loop
Finding arcs within clusters members
Typical cases in A1689
Note the cluster shear effect: testing the potential slope
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
Arc systems with an elliptical lens.
Radial arc
Cusp arc
Einstein Cross
Fold arc
Singly magnified imageof a distant galaxy
From Kneib et al 1993
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 ,
or wo,w1;..
mass evolution
varying
(Ofek, Rix & Maoz 2003) Merger evolution
More information
http://www.cfht.hawaii.edu/~cabanac/SL2S/
The SL2S I:
Cabanac et al. 2006
French/ESA programs
Sloan Lens ACS Survey (SLACS)
Bolton 2004, Treu 2005, Koopmans 2005)Sample ~ 120 candidates with ongoing HST snap
survey
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
O L S
Multiple images formation
Convergence+ shear
+ Fermat principle
gravitational lense effects
From SLACS to CFHTLS rings
Finding rings in the CFHTLS-wide is a great challenge (seeing effect), but if successful SL2S => nring ~ 1500 !
Sciences: Evolution lens parameters with z (profile slope, total mass, M/L,..) at larger redshift (0.2-0.8) than the SLOAN survey (<z>~0.2)
Sloan Lens ACS Survey (SLACS) Bolton 2004, Treu 2005, Koopmans 2005 Study ~ 20/120 candidates with ongoing HST snap survey
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
+
+
<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 or simulation
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
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
Arcs geometry depends on the projection matrix
Projected potential derivatives * Dol . Dls / Dos