Particle Physics Seminar

"Weak Lensing by Galaxy Clusters in the Sloan Digital Sky Survey Stripe 82"

Presented by Melanie Simet Simet, University of Chicago

Wednesday, February 1, 2012, 3:30 pm — Small Seminar Room, Bldg. 510

The shapes of distant galaxies are sheared by intervening galaxy clusters, an effect that can be exploited to obtain information about both dark matter and the expansion history of the Universe. I discuss observations of this effect in the SDSS Stripe 82, a region coadded to create images around 2 magnitudes deeper than the rest of the SDSS survey. We measure masses for about 500 stacked clusters in this region, and we detect tomography, the change in shear with redshift, via a new parameterization. This measurement of tomography is a first step to determining cosmological parameters with cluster lensing. We also show that, due to the sensitivity of the detection to accurate modeling of the lens profiles, we can rule out some dark matter profiles using the tomographic signal. Finally, I will discuss current efforts to determine the locations of the centers of dark matter haloes, an important question for obtaining accurate masses and for understanding the dark matter profiles of clusters.

Hosted by: Erin Sheldon

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