2003ApJ...593..721M

From the analysis of sensitive H I 21 cm line observations, we find evidence for vertically extended H I emission (z≲2.4 kpc) in the edge-on, low surface brightness spiral galaxy UGC 7321. Three-dimensional modeling suggests that the H I disk of UGC 7321 is both warped and flared, but that neither effect can fully reproduce the spatial distribution and kinematics of the highest z-height gas. We are able to model the high-latitude emission as an additional H I component in the form of a ``thick disk'' or ``halo'' with a FWHM of ∼3.3 kpc. We find tentative evidence that the vertically extended gas declines in rotational velocity as a function of z, although we are unable to completely rule out models with constant Vz. In spite of the low star formation rate of UGC 7321, energy from supernovae may be sufficient to sustain this high-latitude gas. However, alternative origins for this material, such as slow, sustained infall, cannot yet be excluded.