# Particle Physics Seminar

## "Magnification and Cosmic Shear from the Sloan Digital Sky Survey"

#### Presented by Eric Huff, UC, Berkeley/LBNL

Tuesday, January 24, 2012, 3:00 pm — Small Seminar Room, Bldg. 510

I discuss results from a cosmic shear measurement in the Sloan Digital Sky Survey. 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 dominated by 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.

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 earlier magnification results. I describe how minor improvements on this work may permit magnification measurements with signal comparable to shear.

Hosted by: Erin Shelden

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