Building up mass in the centers of late type galaxies

We present highest angular resolution (~ 1″ and 0.35″) mm-interferometric observations of the HCN(1-0), ¹²CO(1-0) and ¹²CO(2-1) line emission in the central 300 pc of the late-type spiral galaxy NGC 6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI) shows for the first time a molecular gas spiral in the inner ~ 10″ (270 pc) with a large concentration of molecular gas ($M_{H_2} ∼ 1.6×10^7 M_{\odot}$) within the inner 60 pc, The gas distribution in the central 50 pc has been resolved and is consistent with a gas ring or spiral driven by a bar. Both the distribution of the molecular gas as well as its kinematics can be well explained by the influence of an inner stellar bar of about 400 pc length as tested via a qualitative model for the gas flow. NGC 6946 is a prime example of molecular gas kinematics being driven by a small-scale, secondary stellar bar.