University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Monday, September 11th 2017
12:15 pm:
Speaker: Kelley Hess, Department of Astronomy, University of Cape Town
Subject: Galaxy groups and the assembly of large scale structure

Galaxy groups are the most common environment, and the site where the majority of galaxy evolution occurs. Gas processing--through tidal interactions, ram pressure stripping, viscous stripping, etc--depletes the cold gas, shuts down star formation, and contributes to the build-up of the warm-hot intragroup medium that is sometimes detected in X-rays. As groups accrete more galaxies, the groups themselves become increasingly poor in neutral atomic hydrogen (HI), and more cluster-like. I will present the results of stacking ROSAT All-Sky Survey images for a large sample of groups for which we have complementary HI data from the ALFALFA HI survey in an attempt to detect the build-up of the WHIM in intermediate mass groups M>10^13 M_Sun, where we begin to see the impact of the group environment on the HI content of their member galaxies.

Understanding pre-processing in galaxy groups is in-turn critical to understanding the galaxy cluster population, and in the second half I will present two nearby clusters where we have used wide-field observations in radio, infrared, optical, and X-ray to identify substructure and used the galaxies' kinematics, HI gas, stellar, and hot gas properties to deconstruct the cluster assembly history.

Faculty Host: Liliya L.R. Williams

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