The SDSS Coadd: Cosmic Shear Measurement

TL;DR

This paper analyzes the cosmic shear signal in the Sloan Digital Sky Survey's Stripe 82 region, detecting significant E-mode distortions that inform cosmological parameters like matter density and fluctuation amplitude.

Contribution

It presents the first measurement of cosmic shear using SDSS Stripe 82 data, demonstrating the feasibility of using coadded SDSS images for weak lensing studies.

Findings

E-mode cosmic shear detected at >5-sigma significance

B-mode consistent with zero, indicating low systematics

Constraints on cosmological parameters: Ω_m^{0.7}σ_8 = 0.252^{+0.032}_{-0.052}

Abstract

Stripe 82 in the Sloan Digital Sky Survey was observed multiple times, allowing deeper images to be constructed by coadding the data. Here we analyze the ellipticities of background galaxies in this 275 square degree region, searching for evidence of distortions due to cosmic shear. The E-mode is detected in both real and Fourier space with $>5$-$\sigma$ significance on degree scales, while the B-mode is consistent with zero as expected. The amplitude of the signal constrains the combination of the matter density $\Omega_m$ and fluctuation amplitude $\sigma_8$ to be $\Omega_m^{0.7}\sigma_8 = 0.252^{+0.032}_{-0.052}$.