BAR-DRIVEN FUELING TO A GALACTIC CENTRAL REGION IN A MASSIVE GAS DISC

Using two-dimensional hydrodynamics simulations, we have discovered an effective fuelling process for the central regions of galaxies that h ave weak bar-like distortions. A gravitational instability of an elong ated gas ring at the inner Lindblad resonance (ILR), which has previou sly been reported as an effective fuelling mechanism, is not needed fo r the fuelling process we consider here. In our model, a massive gaseo us disc in the central region of galaxies responds sensitively to the weakly distorted potential, and a large amount of gas can be fed into within 1/20 of a core radius of the potential in several times 10(7) y r. The ILRs, the dissipative nature of the gas, and the self-gravity o f the gas are essential for triggering this effective fuelling. This a ccumulation process has not previously been described. Specifically, t he gas accumulates to form a dense 'linear' structure inclined at abou t 45 degrees with respect to the bar potential in a leading sense. We also found that a counter-rotating gaseous core could be formed as a r esult of the fuelling. The sense of the rotation of the core depends o n the ratio of the gas mass to the background mass. Physical mechanism s of the fuelling process can be understood using a linear theory of g aseous orbits in a weak barred potential.