Wednesday, April 26, 2006

Natarajan: Weak Lensing

UMCP astronomy colloquium by Priya Natarajan from Yale. She summarized the effects of gravitational lensing and described her work deriving the poperties of subhaloes in clusters. She fits a smooth cluster distribution then a subhalo at the position of every cluster galaxy. 10-15% of the mass of the cluster is in the subhaloes which are individually more extended than the visible light of the galaxy. She essentially does a two-parameter fit for the subhalo properties assuming that all subhaloes in the cluster have similar properties. Recent extension of this work which is in press finds evidence for tidal truncation with smaller haloes in the center of the cluster. Finally she talked about prospects for investigating dark energy by comparing the lensing of background objects of different known redshifts. In this case the details of the lens drop out and the distance ratios to the background objects can be determined and hence the cosmology.

Keywords: clusters, lensing

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