|Date||March 20, 2013||Time||4:00 - 5:00 pm|
|Location||Room E.125, Baylor Sciences Building|
|Description||2013 Spring Physics Colloquium Series - Weighing and Measuring Galaxy Clusters, the Most
Massive Objects in the Universe|
Lindsay King, Ph.D.
Associate Professor, Department of Physics
University of Texas at Dallas
Galaxy clusters are the most massive bound objects in the universe, and most of their mass is dark matter that cannot be seen directly with telescopes. Most of their normal baryonic luminous matter is hot X-ray emitting gas, that enshrouds clusters. Stars that shine in galaxies, seen using optical telescopes, account for a smaller amount of this normal matter. Being able to map out the mass in clusters allows key tests of our paradigm for structure formation in the universe, and of the properties of dark matter itself. My talk will begin with an outline of how strong and weak gravitational lensing signatures are used as a tool to study cluster structure. I will then discuss facets of our theoretical and observational research in this area.
One topic that we will consider is how the physics of baryonic matter impacts on the distribution of mass (and hence lensing signatures) in clusters formed in hydrodynamic computer simulations. In particular, I will discuss the importance of the physics of supermassive black holes, hosted by cluster galaxies, in shaping lensing signatures such as the number of giant arcs - highly magnified and distorted images of distant galaxies.
Over the past few years, it has been discovered that "Bullet Clusters" offer a new window on dark matter as well as testing gravity on large scales. These are the most energetic events since the big bang, comprising two or more clusters that have collided in the past - so violently that their dark matter and hot X-ray gas have been separated. Only a handful of these events are known, and we will focus on Abell 2146, a unique system that we are currently investigating.
Room E.125, Baylor Sciences Building
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