Spatial distribution of interstellar gas in the innermost 3 kpc of our galaxy

Abstract

We review the present observational knowledge on the spatial distribution and the physical state of the different (molecular, atomic and ionized) components of the interstellar gas in the innermost 3 kpc of our Galaxy – a region which we refer to as the interstellar Galactic bulge, to distinguish it from its stellar counterpart. We try to interpret the observations in the framework of recent dynamical models of interstellar gas flows in the gravitational potential of a barred galaxy. Finally, relying on both the relevant observations and their theoretical interpretation, we propose a model for the space-averaged density of each component of the interstellar gas in the interstellar Galactic bulge.