ABSTRACT

Self-gravity is a key determinant of gas dynamics, especially in a galactic central region. We have investigated self-gravitating gas dynamics with 2-D PM and SPH methods. From simulations of a massive gas disk inside the first ILR, we found a rapid gas fueling accompanied by a forming gas bar which lead the bar potential. The background bar potential and resonances are not important for dynamics of the central self-gravitaing gas in the accreting stage.

GAS FUELING PROBLEM

Starburst regions are frequently located in the central regions of barred galaxies or interacting galaxies. A number of studies has been made on triggering mechanism of starbursts, that is, mechanism fueling a large amount of gas into the starburst region. Many people believe that oval distortion of a background potential caused by galactic encounters or a stellar bar can trigger the gas rapid fueling. However, a number of numerical simulations which does not take into account the self-gravity of gas have revealed that the distorted potential itself cannot supply a large amount of gas into a galactic center beyond ILRs, although gas accumulate to form an oval ring near ILRs (e.g. Matsuda and Isaka 1980; Schwarz 1985).

SELF-GRAVITY OF THE GAS

Fueling by Collapse of an Elongated Gas Ring

Fukunaga and Tosa (1991), and Wada and Habe (1992) reported that a very elongated gas ring leading a weak background bar potential is formed near ILRs provided that a pattern speed of bar is just below a maximum of ω – k/2.