1. CENTRAL REGIONS OF BARRED GALAXIES: TWO-DIMENSIONAL NON-SELF-GRAVITATING HYDRODYNAMIC SIMULATIONS.
- Author
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WOONG-TAE KIM, WOO-YOUNG SEO, STONE, JAMES M., DOOSOO YOON, and TEUBEN, PETER J.
- Subjects
GALAXIES ,STAR formation ,BLACK holes ,ASTRONOMICAL observations ,STARBURSTS ,GALACTIC nuclei - Abstract
The inner regions of barred galaxies contain substructures such as off-axis shocks, nuclear rings, and nuclear spirals. These substructures may affect star formation, and control the activity of a central black hole (BH) by determining the mass inflow rate. We investigate the formation and properties of such substructures using high-resolution, grid-based hydrodynamic simulations. The gaseous medium is assumed to be infinitesimally thin, isothermal, and non-self-gravitating. The stars and dark matter are represented by a static gravitational potential with four components: a stellar disk, a bulge, a central BH, and a bar. To investigate various galactic environments, we vary the gas sound speed, c
s , as well as the mass of the central BH, MBH . Once the flow has reached a quasi-steady state, off-axis shocks tend to move closer to the bar major axis as cs increases. Nuclear rings shrink in size with increasing cs , but are independent of MBH , suggesting that the ring position is not determined by the Lindblad resonances. Rings in low-cs models are narrow since they are occupied largely by gas on x2 -orbits and well decoupled from nuclear spirals, while they become broad because of large thermal perturbations in high-cs models. Nuclear spirals persist only when either cs is small or MBH is large; they would otherwise be destroyed completely by the ring material on eccentric orbits. The shape and strength of nuclear spirals depend sensitively on cs and MBH such that they are leading if both cs and MBH are small, weak trailing if cs is small and MBH is large, and strong trailing if both cs and MBH are large. While the mass inflow rate toward the nucleus is quite small in low-cs models because of the presence of a narrow nuclear ring, it becomes larger than 0.01 Mโ yr-1 when cs is large, providing a potential explanation of nuclear activity in Seyfert galaxies. [ABSTRACT FROM AUTHOR]- Published
- 2012
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