Ionization of Infalling Gas
The Role of the Disk-Halo Interaction in Galaxy Evolution: Outflow vs. Infall? Edited by M.A. de Avillez. EAS Publication Series, Volume 56, 2012, pp.319-322
Published in Sep 2012
Hα emission from neutral halo clouds probes the radiation and hydrodynamic conditions in the halo. Armed with such measurements, we can explore how radiation escapes from the Galactic plane and how infalling gas can survive a trip through the halo. The Wisconsin H-Alpha Mapper (WHAM) is one of the most sensitive instruments for detecting and mapping optical emission from the ISM. Here, we present recent results exploring the ionization of two infallling high-velocity complexes. First, we report on our progress mapping Hα emission covering the full extent of Complex A. Intensities are faint (100 mR; EM 0.2pccm-6) but correlate on the sky and in velocity with 21-cm emission. Second, we explore the ionized component of some Anti-Center Complex clouds studied by Peek et al. (2007) that show dynamic shaping from interaction with the Galactic halo.