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XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Cosmic shear using Canada-France-Hawaii
Telescope Legacy Survey (Wide)
Liping FuInstitut d’Astrophysique de Paris
"From giant arcs to CMB lensing: 20 years of gravitational distortion"
XXIIIrd IAP Colloquium July 2nd, 2007
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Canada:H. Hoekstra (U. Victoria)L. van Waerbeke (UBC, Vancouver)C. Heymans (UBC/IAP)J. Benjamin (UBC)S. Gwyn (U. Victoria)M. Hudson (U. Waterloo)L. Parker (U. Waterloo/ESO)B. Menard (CITA) U.L. Pen (CITA)O. Dore(CITA)
CollaborationFrance:L. Fu (IAP)E. Semboloni (Bonn/IAP)I. Tereno (Bonn/IAP) Y. Mellier (IAP)M. Kilbinger (IAP)J. Coupon (IAP)E. Bertin (IAP)H.J. McCracken (IAP)O. Ilbert (UBDA)K. Benabed (IAP)
R. Maoli (U.Rome/IAP)F. Bernardeau (CEA/SPhT)M. Dantel-Fort (LERMA)F. Magnard (IAP)C. Marmo (IAP)M. Schultheis (Obs. Besançon)J.P. Uzan (IAP)C. Schimd (CEA/SPP and IAP)
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Outline Introduction to CFTHLS
Pipeline reliability
Cosmic shear on large scales
Cosmological parameter
constraints
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
I. Canada-France-Hawaii Telescope Legacy Survey
XXIIIrd IAP Colloquium, July 2nd 2007, ParisTerapix/Skywatcher : all data 03A-05A : 20000 Megacam images
W2D4
W3 & D3D2
Canada-France-Hawaii Telescope Legacy Survey: Canada-France collaboration - 500 nights between June 2003 and June 2008
- 4 CFHTLS-Wide ( 170 deg2 ), 4 CFHTLS-Deep ( 1 deg2 each )
HST Groth strip
GEMINI-N visibility
VLT visibility VLT visibility + XMM fields
VVDS spectro. survey
VLT visibility
+ HST-Cosmos VLT visibility +
Quasar fieldW1 & D1
3.6 m ground telescope3.6 m ground telescope
MegaCam: 36 CCDs, 1MegaCam: 36 CCDs, 1oo × 1 × 1oo
Pixel size: 0.186”Pixel size: 0.186”
u g r i z bandsu g r i z bands
W4 VVDSUKIDSS DXS
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
W1 (19 deg2) W2 (8 deg2) W3 (30 deg2)
Sky coverage of CFHTLS Wide (the 3rd release): 57 deg2
Number of Pairs
CFHTLS Wide:
57 deg2 (35% completed)
W2 is new compared with 1st release
maglim= 24.5 i-band
Aeff= 35 deg2 (conservative
masking); neff = 12 gal/arcm2
2.5 ×106 galaxies
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
II. Pipeline reliability
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
the multiplicative “calibration bias”the multiplicative “calibration bias” the additive “residual shear offset”the additive “residual shear offset”
Unbiased shear measurement on Shear TEsting Program (STEP; see Kuijken’s talk)
STEP1 STEP2
“0,…5” & “A,…F”: Realistic PSF models in simulations
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
III. Cosmic shear on large scales using CFHTLS Wide (the 3rd release)
Two publication (the 1Two publication (the 1stst release): release): Semboloni et al., 2006 (Deep)Semboloni et al., 2006 (Deep) Hoekstra et al., 2006 (Wide)Hoekstra et al., 2006 (Wide)
Cosmic shear signal on large scales
• Sky coverage: 57 deg2• up to 460’
up to: 230’• No B-mode• Error bars (Schneider et al. 2002) :
BNGcvmixpoi CCCCC ,
Non-Gaussianity calibrated(Semboloni et al. 2006)
2apM 2
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Large scales zoom in (26’~230’)
Reliable Shear analysis till 4 degrees
Large scales signal will reduce the effect of small scales systematics (non-linear evolution of power spectrum; intrinsic alignment)
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
The consistency of W1, W2 and W3
Scales up to:Scales up to:
W1 200’ (19 degW1 200’ (19 deg22) )
W2 120’ (8 degW2 120’ (8 deg22) )
W3 230’ (30 degW3 230’ (30 deg22) )
2pt correlation functions2pt correlation functions
Consistency !Consistency !
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Shear cross checking and systematics Consistent shear signal
Common objects using two independent pipelines:
French: LF = L. Fu
Canadian: HH = H. Hoekstra
No systematics
**
2*
sys uncoruncor
coruncor
ee
e
French
Canadian
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
IV. Cosmological parameter constraints
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Redshift distribution
a single lens-plane +
)2(
1.5s
1.6M
28
222
deg1 z 0.01 )(~
n
e
CFHTLS Deep Photo-z (500,000 galaxies, Ilbert et al. 2006)
z
• Less complete
• WL selection criteria
• WL weighting scheme
Shear and cosmological parameters
21.5 < mag_i < 24.5
<z> = 0.926
Error bars:
photo-z uncertainty + poisson error + sample variance (van Waerbeke et al, 2006)
0 1 2 3 4 z
cz
zNn
b
a
z
Bootstrap
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
2
D)&(P 0.06 0.73
0.29
0.57
m8
2apM
2
• flat model
• likelihood of CS: , grid (other parameters are fixed)
• likelihood of ; taken as a prior
•
CDM),,( 8 hm
)2(];8.0,6.0[ znh
),,( cbanz
)( 0.06 0.72
0.28
0.59
m8
Sm
Non-linear scheme: halo-fit
Non-linear scheme: P&D (1996) and halo-fit (Smith et al., 2003)
Marginalization:
),,( cbanz
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Comparison of constraints from different scales
1’~230’ 26’~230’
• Full scales constraints: 2% difference
• No small scales constraints: less than 1% difference
• Systematics?
Compare P&D and halo-fit model:
3.0m
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Comparison with Benjamin et al., 2007
Comparison with previous constraints
100 deg2
CFHTLS Wide
+ RCS
+ VIRMOS-DESCART
+ GaBoDS
CFHTLS-wide (1st)Aeff = 22 deg2
CFHTLS-wide (3rd)Aeff = 35 deg2
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Comparison with WMAP3 (Spergel et al., 2006)
WMAP3
CFHTLS Wide (3rd)
)( 0.06 0.72 0.28
0.59
m8 Sm
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Non-linear power spectrum (Peacock & Dodds, 1996) Marginalizing over Flat model
62.00 w (68% c.l.)
The constant equation of state:
]8.0,6.0[;733.08 hCDM
Probing dark energy
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Conclusion Unbiased shear measurement calibrated on simulations and cross-che
cked with independent pipeline Reliable Shear analysis up to large scales : 4 degrees The use of large scales reduce the effect of small scales systematics (no
n-linear evolution of power spectrum; intrinsic alignment) The cosmological parameter constraints (68% c.l.)
Constraints consistent with WMAP3 The redshift degeneracy will be further minimized with the photometri
c redshifts measured from the new release (T4, Work in progress)
62.00 w)( 0.06 0.72 0.28
0.59
m8 Sm
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Covariance matrix
Gaussian covariance matrix taking masking and survey geometry into account (Schneider et al. 2002)
Non-Gaussian calibration (Semboloni et al. 2006) ),( ),(),( 212121, cvNGNGcv CFC
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Weighting scheme of weak lensing
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
= s + i + noise + systematics….
Weak lensing and Galaxy shape:
Weak lensing regime : ~ 2 = ‹Shear› + noise
Assume sources orientation is isotropic:
Mellier 1999
δ ~ 2γ (weak lensing regime)
PSF anisotropy correction
Derived from star shape analysis.
Reliability of results: depends on PSF analysis
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Cosmic shear probes the dark matter power Cosmic shear probes the dark matter power spectrumspectrum
Two-point statistics
Convergence (projected mass) power spectrum
( Blandford et al 1991, Miralda-Escudé 1991, Kaiser 1992,1998, Bernardeau et al 1997, Jain & Seljak 1997, Schneider et al 1998 )
Redshift Redshift distributiondistribution
2D power spectrum2D power spectrum
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Expansion and growth rate of structures as function of DM and DE content of the universe
Supernovae Weak lensing
a Goal of CFHTLS Cosmic Shear Survey:
observe P(k) and P(k,z) using weak lensing and compare its properties with cosmological models.
XXIIIrd IAP Colloquium, July 2nd 2007, Paris
Weak gravitational lensing and cosmology:Light propagation in inhomogeneous universes
Bartelmann & Schneider 2001; Erben 2002
ds2=c2dt2 - a2(t) [dw2 + fK2(w) d2]
Deflection angle:
Distances (Geometry)Power spectrum, growth rate of structure
Depend on dark matter and dark energy
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