HI in the inner few kiloparsecs of the galaxy

Abstract

After reviewing the available observational material, we describe here a simple model of the distribution and kinematics of HI gas within 1.5 kpc of the galactic center. According to this model, most of the inner-Galaxy gas is smoothly distributed in a tilted disk, within which the perceived kinematics are consistent with axisymmetric rotation and expansion of approximately equal magnitude. The model subsumes in a coherent way many observed spectral features which were previously studied separately, without requiring important density enhancements or anisotropic ejection from the nucleus.