Probing Galactic-Scale Outflows and Co-Rotating Halo Gas Towards a Compact Massive Galaxy

Type Conference Paper
Names Aleksandar M. Diamond-Stanic, A. Coil, J. Moustakas, C. Tremonti, R. Hickox, A. Mendez, A. Robaina, G. Rudnick, P. Sell
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #219, #322.01
Volume 219
Date January 1, 2012
Library Catalog NASA ADS
Abstract The interplay between inflows and outflows of gas around galaxies has wide-ranging implications for galaxy evolution. We present results for a serendipitous background / foreground galaxy pair based on HST/WFC3 imaging, Keck/HIRES spectroscopy, and GALEX--Spitzer/IRAC photometry. The background galaxy is a massive (stellar mass 1011 solar masses) post-starburst galaxy at z=0.71 with an extremely compact morphology (effective radius 0.15 kpc) and an extreme outflow (velocity -2500 km/s) traced by Mg I, Mg II, Fe II, and Mn II absorption lines. The depth of the Mg II absorption lines show that the outflowing gas covers the entire galaxy at v -2500 km/s with additional optically thick, smaller covering factor gas extending to -3000 km/s. These results suggest a picture where a recent, highly dissipative merger event formed a compact starburst that launched an energetic, galaxy-wide outflow. The foreground object is an L* disk galaxy at z=0.41 for which we detect Mg II and Fe II absorption lines at a 30 kpc impact parameter. These absorption lines are offset from the foreground galaxy redshift by 200 km/s, consistent with an extension of the galaxy's rotation curve and consistent with theoretical predictions for inflowing gas that co-rotates in the galaxy halo before falling onto the galaxy disk. We discuss the implications of these results for models of gas accretion and feedback.
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