Date/Time
Date(s) - 25/09/2006
1:30 pm - 2:30 pm

Title: Probing galaxies and their dark matter halos with gravitational lensing

Speaker: Dr. Laura Parker

Institute: European Southern Observatory
Germany

Location: ABB 271

Description:

Despite the now overwhelming evidence that indicates most of the matter in the universe consists of some unknown ‘dark matter’, its properties and role in the evolution of galaxies are not well understood. One of the most useful techniques for studying dark matter is gravitational lensing. In this talk I will start by summarizing our current understanding of cosmology and evidence for dark matter, with emphasis placed on measurements using lensing.

In the second part of the talk I will focus on two observational projects using weak gravitational lensing to link galaxies and groups of galaxies to the properties of their dark matter halos. The first project is a study of galaxy groups measuring their masses and mass-to-light ratios using lensing. The results indicate that groups play an important role in galaxy evolution– defining the environment where star formation in galaxies is quenched. The second project uses data from a large Canadian and French survey to study the dark matter halos of galaxies. The average properties of galaxy halos are investigated including their shapes, which can be used to constrain alternative theories of gravity. I will conclude with a look at future projects and instruments being planned to tackle some of the many remaining questions in observational cosmology.