2003ApJ...597...98H

We present measurements of the cosmic shear correlation in the shapes of galaxies in the Suprime-Cam 2.1 deg² R_C-band imaging data. As an estimator of the shear correlation originating from the gravitational lensing, we adopt the aperture mass variance, which most naturally decomposes the correlation signal into E and B (non-gravitational lensing) modes. We detect a nonzero E mode variance on scales between θ_ap=2' and 40'. We also detect a small but nonzero B-mode variance on scales larger than θ_ap>5'. We compare the measured E-mode variance to the model predictions in CDM cosmologies using maximum likelihood analysis. A four-dimensional space is explored, which examines σ₈, Ω_m, Γ (the shape parameter of the CDM power spectrum), and z{d1}_s(mean redshift of galaxies). We include three possible sources of error: statistical noise, the cosmic variance estimated using numerical experiments, and a residual systematic effect estimated from the B-mode variance. We derive joint constraints on two parameters by marginalizing over the two remaining parameters. We obtain an upper limit of Γ<0.5 for z{d1}_s>0.9 (68% confidence). For a prior Γ∈[0.1,0.4] and z{d1}_s∈[0.6,1.4], we find σ₈=(0.50^+0.35_–0.16)Ω^–0.37_mfor Ω_m+Ω_Λ=1 and σ₈=(0.51^+0.29_–0.16)Ω^–0.34_mfor Ω_Λ=0 (95% confidence). If we take the currently popular ΛCDM model (Ω_m=0.3, Ω_λ=0.7, Γ=0.21), we obtain a one-dimensional confidence interval on σ₈for the 95.4% level, 0.62<σ₈<1.32 for z{d1}_s∈[0.6,1.4]. Information on the redshift distribution of galaxies is key to obtaining a correct cosmological constraint. An independent constraint on Γ from other observations is useful to tighten the constraint.