Investigating Disk-Halo Flows and Accretion: A Kinematic and
  Morphological Analysis of Extraplanar HI in NGC 3044 and NGC 4302
  To further understand the origins of and physical processes operating in
extra-planar gas, we present observations and kinematic models of HI in the two
nearby, edge-on spiral galaxies NGC 3044 and NGC 4302. We model NGC 3044 as a
single, thick disk. Substantial amounts of extra-planar HI are also detected.
We detect a decrease in rotation speed with height (a lag) that shallows
radially, reaching zero at approximately R25. The large-scale kinematic
asymmetry of the approaching and receding halves suggests a recent disturbance.
The kinematics and morphology of NGC 4302, a Virgo Cluster member, are greatly
disturbed. We model NGC 4302 as a combination of a thin disk and a second,
thicker disk, the latter having a hole near the center. We detect lagging
extra-planar gas, with indications of shallowing in the receding half, although
its characteristics are difficult to constrain. A bridge is detected between
NGC 4302 and its companion, NGC 4298. We explore trends involving the
extra-planar HI kinematics of these galaxies, as well as galaxies throughout
the literature, as well as possible connections between lag properties with
star formation and environment. Measured lags are found to be significantly
steeper than those modeled by purely ballistic effects, indicating additional
factors. Radial shallowing of extra-planar lags is typical and occurs between
0.5R25 and R25, suggesting internal processes are important in dictating
extra-planar kinematics.
