Colloquium on Jun. 17, 2021

Testing the cosmological model with the help of weak gravitational lensing

Speaker: Tim Schrabback (University of Bonn)

Venue: Video Conference

Time: 16:00 PM, Thursday, Jun. 10, 2021

Abstract:

The Universe appears to be dominated by dark matter (driving the growth of structure) and dark energy (driving the late-time accelerated expansion). Together, these invisible components contribute to 95% of the cosmic energy budget. Yet, their physical nature is still unclear. A powerful tool to learn more about them is weak gravitational lensing, which describes image distortions that are imprinted onto the shapes of background galaxies when their light passes through the gravitational potential of foreground matter concentrations. These distortions can be measured statistically, enabling a wide range of cosmological applications. As primary focus of this talk I will present efforts done within the South Pole Telescope (SPT) collaboration, which aim to constrain cosmology via the SPT galaxy cluster counts and complementary weak lensing measurements of the absolute cluster mass scale. I will also summarize recent results that test the dark matter model by constraining the ellipticity of galaxy-scale dark matter halos using weak lensing. In the context of cosmological weak lensing studies, which constrain large-scale structure statistics by correlating the shapes of background galaxy pairs, I will illustrate some of the technical issues based on earlier work done with the Hubble Space Telescope, summarize recent results, and provide an outlook into the future.

Report PPT:  SWIFAR_Tim Schrabback.pdf