Mathematics – Logic
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21741205k&link_type=abstract
American Astronomical Society, AAS Meeting #217, #412.05; Bulletin of the American Astronomical Society, Vol. 43, 2011
Mathematics
Logic
Scientific paper
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. The dynamics of this gas is likely driven by one or more of the following physical processes: supernovae ejecta, stellar winds, minor mergers, and inflow via filaments or satellites. In an effort to gain an understanding of how halos are built and evolve in a cosmological context, we directly compare the MgII halo gas kinematics to the rotation velocities derived from emission/absorption lines of their host galaxies. Our volume-limited sample of 11 z=0.1 MgII absorption systems are associated with 13 galaxies located at projected distances of 12-90 kpc from the quasar line-of-sight. In half of our sample the MgII absorption reside to one side of the galaxy systemic velocity and aligns with one side of its rotation curve. In the remaining half, the absorption spans both sides of the galaxy systemic velocity, although the bulk of the MgII resides mostly to one side of the galaxy systemic velocity.
We find that extended disk-like rotation models fail to reproduce the MgII velocity spread in all but one case, implying additional dynamical processes (outflow/infall) must be invoked to explain the observed range of MgII absorption velocities. In addition, intrinsic host galaxy NaI and MgI absorption line ratios suggest that these galaxies do not host strong outflows, which is also consistent with their low star formation rates. These results provide strong evidence that the MgII absorbers are associated with the infalling gas which is fueling galaxy star formation.
Barton Elizabeth J.
Churchill Christopher W.
Cooke Jeff
Kacprzak Glenn G.
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