Seeing in the Dark: Cosmic Shear in SDS

Eric Huff
(UC Berkeley)


I discuss preliminary results from a first cosmic shear measurement in SDSS. We have coadded 250 square degrees of multi-epoch SDSS imaging along the celestial equator, optimizing for weak lensing measurement. We employ standard techniques for shape measurement, shear calibration, and inference of the redshift distribution, and perform a wide array of tests that show that the systematic errors for this measurement are probably negligible compared to the statistical errors. We analyze the shear autocorrelation with and without WMAP7 priors, and produce competitive constraints on the matter density and the amplitude of the matter power spectrum at redshift z=0.6.

I will also discuss some new results on lensing magnification. Motivated by the need for greater signal-to-noise in weak lensing measurements, we have used tight photometric galaxy scaling relations to measure a galaxy-galaxy magnification signal with many times the signal-to-noise of previous magnification results. I describe how minor improvements on this work may permit magnification measurements with signal comparable or possibly even superior to shear.