Bar-disc angular momentum exchange

Abstract

A model galaxy with an artificial bar is used to explore the angular momentum exchange induced by bar-like (m = 2) perturbations to a disc. An analytic formula is provided for this exchange which predicts to within ∼1 per cent the interaction between a weak bar and a non-self-gravitating disc. The results of N-body experiments are also presented, which suggest that the neglect of disc self-gravity in analytic theory leads to : (i) an underestimate of the slowdown rate of a bar which is dominated by corotation and outer Lindblad resonances; (ii) an overestimate of the spin-up rate of a bar which is dominated by inner Lindblad resonances