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Physics & Astronomy Colloquium
October 11 @ 3:30 pm - 5:00 pm
Speaker: Christy Tremonti (University of Wisconsin-Madison)
Title: Gone with the Wind? Galactic winds and star formation quenching
Abstract: The massive elliptical galaxies are believed to have formed most of their stars in short duration bursts early in the Universe’s history (z > 3). A lingering mystery is what causes star formation to shut off so abruptly in these systems. To gain insight, we are studying a sample of lower redshift (z=0.4-0.8) analogs selected to be in the earliest phases of star formation quenching. Using a combination of Hubble and Chandra imaging, CO molecular line data, and ground-based spectroscopy, we show that the galaxies have undergone incredibly compact central starbursts where star formation proceeds at close to the theoretical maximum rate. The galaxies drive impulsive, high velocity (v > 1000 km/s) gas outflows which remove a substantial amount of fuel for future star formation. We hypothesize that the compactness of the central starburst is the key to driving powerful gaseous winds and shutting off star formation. Black hole activity, which has frequentely been invoked to explain quenching, may not be required.
Christy Tremonti is an assistant professor in the Astronomy department at the University of Wisconsin, Madison. Her research is focused on galaxy evolution, in particular the processes that help regulate star formation. She is an observational astronomer with a strong interest in spectroscopy from UV to IR wavelengths. She also an avid “data miner” and is a member of the Sloan Digital Sky Survey III (SDSS-III) collaboration. Before joining the faculty at the UW-Madison, Christy was a Humboldt fellow at the Max Planck Institute for Astronomy in Heidelberg Germany and a Hubble postdoctoral fellow at the University of Arizona. She was educated at Colgate University (B.A. 1990) and Johns Hopkins University (Ph.D. 2003).