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Resolving the Small-Scale Structure of the Cool Circumgalactic Medium

Kate Rubin, San Diego State University
Thursday, October 20, 2016 - 4:00pm to 5:00pm
PAA A-102

​The environments extending several hundred kiloparsecs from galaxies contain the fuel that feeds galactic star formation, and act as the reservoir into which ejecta from stellar and AGN feedback are driven. Observations of the cool hydrogen and metal content, kinematics, and morphology in these regions (i.e., the circumgalactic medium, or CGM) can therefore provide incisive tests of our understanding of these processes. Background quasar spectroscopy has long been the tool of choice for such observations; however, spectroscopy of bright galaxies can also be used to study the halos of galaxies in the foreground (as well as their own). Moreover, galaxies offer background beams many orders of magnitude larger than those provided by QSOs and may be spatially resolved with modern IFUs. I will discuss the first systematic survey to use this technique to characterize cool gas in individual foreground galaxy halos, reporting a unique constraint on the morphology of MgII absorption in the z~0.5 CGM. I will then describe new measurements of gas flows made possible with the spatially-resolved galaxy spectroscopy being obtained by the SDSS-IV/MaNGA survey, demonstrating MaNGA’s potential for establishing the frequency and cross section of gas accretion onto galaxies. Such three-dimensional study is crucial to understanding the thermodynamics of the gas flows which regulate galaxy growth.

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