Kinematics of Atomic Gas Halos in Edge-on Spirals

Richard Rand (UNM)

We report recent results on the atomic layer of the massive edge-on spiral NGC 5746, and present new constraints on lagging atomic halos in the edge-ons NGC 4244 and NGC 4565. NGC 5746 is an excellent candidate in which to search for infall of warm, primordial gas. Our VLA maps reveal extensive extraplanar gas, but it is better modeled as a warp along the line of sight than as a halo. However, a few extraplanar clouds are found at velocities distinct from the warp. These could be infalling clouds or part of a weak disk-halo cycle. From WSRT data, there is little evidence for a rotational lag in the halos of NGC 4244 and NGC 4565.