Schedule Feb 17, 2012
A SHARP-eyed Search for Substructure around Distant Galaxies
Chris Fassnacht (UC Davis)

I will present results from the Strong-lensing High Angular Resolution Program (SHARP), which has among its goals detecting and measuring the masses of substructures associated with galaxies at redshifts between 0.3 and 1.0. This program takes advantage of high angular resolution imaging provided by Keck adaptive optics observations and the power of gravitational lensing to measure the masses of objects. Furthermore, because the lensing effect does not require the substructure to be luminous or baryonic, this program can in principle detect objects that are purely dark matter. Thus, with this technique we can provide direct observational comparisons to simulations of galaxy formation, using galaxies outside the Local Group. We have recently detected a substructure with mass of ~2 x 10^8 solar masses (Vegetti et al. 2012), showing the power of this approach. By building up a sample of galaxies that we have surveyed with this program we will be able to place meaningful constraints on both the fraction of mass contained in subhalos and the slope of the substructure mass function.


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