Particle Physics Seminar

In this first half of this talk, I will present new results on the relationship between X-ray luminosity (Lx) and dark matter halo mass
(M200) for an ensemble of 200 X-ray selected groups where halo masses have been derived via stacked weak gravitational lensing in the COSMOS survey. Extending weak lensing measurements into the group regime is particularly important in order to extend the dynamic range of weak- lensing-based mass-estimates so as to more accurately determine the slopes of scaling relations. Measurements of the form and evolution of X-ray scaling laws are critical for both improving cosmological constraints derived with the halo mass function and for understanding the physical processes that govern the heating and cooling of the intracluster medium. This work draws upon a broad array of multi- wavelength COSMOS observations including 1.64 square degrees of contiguous imaging with the Advanced Camera for Surveys (ACS) and deep XMM-Newton/Chandra imaging. The combined depth of these two data-sets allows us to probe the lensing signals of X-ray detected structures at both higher redshifts and lower masses than previously explored.
In the second half of this talk, I will present a variety of other ongoing projects in COSMOS including our efforts to constrain the relationship between halo mass and galaxy stellar mass using galaxy- galaxy lensing techniques, looking at the dark matter halos of AGN using weak lensing, and the properties of galaxies in group environments.