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Cosmic shear statistics in the Suprime-Cam 2.1 sq deg field: Constraints on Omega_m and sigma_8

Research paper by T. Hamana, S. Miyazaki, K. Shimasaku, H. Furusawa, M. Doi, M. Hamabe, K. Imi, M. Kimura, Y. Komiyama, F. Nakata, N. Okada, S. Okamura, M. Ouchi, M. Sekiguchi, M. Yagi, et al.

Indexed on: 11 Jul '03Published on: 11 Jul '03Published in: Astrophysics



Abstract

We present measurements of the cosmic shear correlation in the shapes of galaxies in the Suprime-Cam 2.1 deg^2 R_c-band imaging data. As an estimator of the shear correlation originated from the gravitational lensing, we adopt the aperture mass variance. We detect a non-zero E mode variance on scales between 2 and 40arcmin. We also detect a small but non-zero B mode variance on scales larger than 5arcmin. 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 sigma_8, Omega_m, Gamma and zs (a 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 Gamma<0.5 for zs>0.9 (68% confidence). For a prior Gamma\in[0.1,0.4] and zs\in[0.6,1.4], we find sigma_8=(0.50_{-0.16}^{+0.35})Omega_m^{-0.37} for flat cosmologies and sigma_8=(0.51_{-0.16}^{+0.29})Omega_m^{-0.34}$ for open cosmologies (95% confidence). If we take the currently popular LCDM model, we obtain a one-dimensional confidence interval on sigma_8 for the 95.4% level, 0.62<\sigma_8<1.32 for zs\in[0.6,1.4]. Information on the redshift distribution of galaxies is key to obtaining a correct cosmological constraint. An independent constraint on Gamma from other observations is useful to tighten the constraint.