Abstract
We investigate the dependence of gas kinematics and column densities in the
MgII-absorbing circumgalactic medium on galaxy color, azimuthal angle, and
inclination to trace baryon cycle processes. Our sample of 30 foreground
isolated galaxies at $0.3<z_gal<1.0$, imaged with the Hubble Space
Telescope, are probed by background quasars within a projected distance of
$20<D<110$ kpc. From the high-resolution ($\Delta v6.6$ km s$^-1$)
quasar spectra, we quantify the extent of the absorber velocity structure with
pixel-velocity two-point correlation functions. Absorbers with the largest
velocity dispersions are associated with blue, face-on ($i<57^\circ$)
galaxies probed along the projected minor axis ($\Phi 45^\circ$), while
those with the smallest velocity dispersions belong to red, face-on galaxies
along the minor axis. The velocity structure is similar for edge-on ($i \geq
57^\circ$) galaxies regardless of galaxy color or azimuthal angle, for red
galaxies with azimuthal angle, and for blue and red galaxies probed along the
projected major axis ($\Phi<45^\circ$). The cloud column densities for
face-on galaxies and red galaxies are smaller than for edge-on galaxies and
blue galaxies, respectively. These results are consistent with biconical
outflows along the minor axis for star-forming galaxies and accreting and/or
rotating gas, which is most easily observed in edge-on galaxies probed along
the major axis. Gas entrained in outflows may be fragmented with large velocity
dispersions, while gas accreting onto or rotating around galaxies may be more
coherent due to large path lengths and smaller velocity dispersions. Quiescent
galaxies may exhibit little-to-no outflows along the minor axis, while
accretion/rotation may exist along the major axis.
Description
[1505.07167] MAGIICAT V. Orientation of Outflows and Accretion Determine the Kinematics and Column Densities of the Circumgalactic Medium
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