XXIIIrd IAP Colloquium, July 2nd 2007, Paris Cosmic shear using Canada-France-Hawaii Telescope Legacy Survey (Wide) Liping Fu Institut d’Astrophysique

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


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)


Outline Introduction to CFTHLS

Pipeline reliability

Cosmic shear on large scales

Cosmological parameter

constraints


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


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


II. Pipeline reliability


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


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


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)


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 !


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


IV. Cosmological parameter constraints


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


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


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


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


Comparison with WMAP3 (Spergel et al., 2006)

WMAP3

CFHTLS Wide (3rd)

)( 0.06 0.72 0.28

0.59

m8 Sm


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


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



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


Weighting scheme of weak lensing


= 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


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


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.


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

Documents

XXIIIrd IAP Colloquium, July 2nd 2007, Paris Cosmic shear using Canada-France-Hawaii Telescope Legacy Survey (Wide) Liping Fu Institut d’Astrophysique