A Dynamical Study of Extraplanar Diffuse Ionized Gas in NGC 5775
  The structure and kinematics of gaseous, disk-halo interfaces are imprinted
with the processes that transfer mass, metals, and energy between galactic
disks and their environments. We study the extraplanar diffuse ionized gas
(eDIG) layer in the interacting, star-forming galaxy NGC 5775 to better
understand the consequences of star-formation feedback on the dynamical state
of the thick-disk interstellar medium (ISM). Combining emission-line
spectroscopy from the Robert Stobie Spectrograph on the Southern African Large
Telescope with radio continuum observations from Continuum Halos in Nearby
Galaxies - an EVLA Survey, we ask whether thermal, turbulent, magnetic field,
and cosmic-ray pressure gradients can stably support the eDIG layer in
dynamical equilibrium. This model fails to reproduce the observed exponential
electron scale heights of the eDIG thick disk and halo on the northeast
($h_{z,e} = 0.6, 7.5$ kpc) and southwest ($h_{z,e} = 0.8, 3.6$ kpc) sides of
the galaxy at $R < 11$ kpc. We report the first definitive detection of an
increasing eDIG velocity dispersion as a function of height above the disk.
Blueshifted gas along the minor axis at large distances from the midplane hints
at a disk-halo circulation and/or ram pressure effects caused by the ongoing
interaction with NGC 5774. This work motivates further integral field unit
and/or Fabry-Perot spectroscopy of galaxies with a range of star-formation
rates to develop a spatially-resolved understanding of the role of
star-formation feedback in shaping the kinematics of the disk-halo interface.
