Cosmic Shear Statistics in the Suprime-Cam 2.1 Square Degree Field: Constraints on Ωm and σ8
Abstract
We present measurements of the cosmic shear correlation in the shapes of galaxies in the Suprime-Cam 2.1 deg2 RC-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 θap=2' and 40'. We also detect a small but nonzero B-mode variance on scales larger than θap>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, Ωm, Γ (the shape parameter of the CDM power spectrum), and zs (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 zs>0.9 (68% confidence). For a prior Γ∈[0.1,0.4] and zs∈[0.6,1.4], we find σ8=(0.50+0.35-0.16)Ω-0.37m for Ωm+ΩΛ=1 and σ8=(0.51+0.29-0.16)Ω-0.34m for ΩΛ=0 (95% confidence). If we take the currently popular ΛCDM model (Ωm=0.3, Ωλ=0.7, Γ=0.21), we obtain a one-dimensional confidence interval on σ8 for the 95.4% level, 0.62<σ8<1.32 for zs∈[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.
Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.- Publication:
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The Astrophysical Journal
- Pub Date:
- November 2003
- DOI:
- 10.1086/378348
- arXiv:
- arXiv:astro-ph/0210450
- Bibcode:
- 2003ApJ...597...98H
- Keywords:
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- Cosmology: Cosmological Parameters;
- Cosmology: Observations;
- Cosmology: Dark Matter;
- Cosmology: Gravitational Lensing;
- Astrophysics
- E-Print:
- 12 pages, 12 figures, accepted for publication in ApJ