Effects of gas on the formation and evolution of a bar in Milky-Way sized galaxies
Abstract
To study the effects of a gas component on the formation and evolution of a stellar bar, we run fully self-consistent three-dimensional simulations of isolated barred galaxies similar to the Milky Way. Our models consider feedbacks from star formation and accretion to a black hole, but neglect the effects of magnetic fields. We vary the gas fraction in the disk as well as the Toomre stability parameter Q in the stellar disk. In models with Q=1.2, the presence of gas tends to delay the bar formation and make a bar weaker since the gas disk does not actively participate in a bar-forming large-scale gravitational instability. In models with Q=1.0, on the other hand, the gas rapidly turns into stars with low velocity dispersions, which cools down the stellar disk and thus promotes the bar formation. While gas-free disks are subject to buckling instability, disks with the gas fraction more than 5% are found to thicken secularly without undergoing the buckling instability. A stellar bar that forms is efficient in redistributing the gas in the bar regions and produces a star-forming nuclear ring. The ring is very small when it first forms and grows in size over time. The bars and nuclear rings formed in our models have properties similar to the central molecular zone in the Milky Way.
- Publication:
-
American Astronomical Society Meeting Abstracts #231
- Pub Date:
- January 2018
- Bibcode:
- 2018AAS...23125714S