Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

Tracing Outflows and Accretion: A Bimodal Azimuthal Dependence of the Circumgalactic Medium (#85)

Glenn G. Kacprzak 1 , Chris W. Churchill 2 , Nikole M. Nielsen 2
  1. Swinburne University of Technology, Hawthorn, VIC, Australia
  2. Department of Astronomy , New Mexico State University, Las Cruces, NM, USA
MgII absorption-lines detected in the spectra of background quasars allow us to probe the cool metal-enriched halo gas associated with foreground galaxies. This technique allows us to directly study the complex halo gas which provides the fuel for star-forming disks.  We will discuss the series of observations that likely explain the origins of MgII absorption systems.  We will present how the orientation of foreground absorbing galaxies influences the MgII absorption strengths and gas covering fractions as probed with background quasars/galaxies. We will show the bi-model distribution of galaxy positions angles, relative to the background source, demonstrating that the absorption arises along the projected galaxy minor and major axis. This suggests that the absorption arises from outflows along the minor axis and accretion along the major axis.  We show how the predictions of simple outflow and inflow models are consistent with these observations.