Simulations of Nuclear Star-Forming Rings: A Case of the Milky Way

Abstract

Gas materials in the inner Galactic disk continuously migrate toward the Galactic center (GC) due to interactions with the bar potential, magnetic fields, stars, and other gaseous materials. Those in forms of molecules appear to accumulate around 200 pc from the center (the central molecular zone, CMZ) to form stars there and further inside. The bar potential in the GC is thought to be responsible for such acculmulation of molecules and subsequent star formation, which is believed to have been continous throughout the lifetime of the Galaxy. We present hydrodynamic simulations of gas clouds in the central kpc region of the Milky Way that is modeled with a three-dimensional bar potential. Our simulations consider realistic gas cooling and heating, star formation, and supernova feedback. A torus of dense gas clouds forms as a result of X1–X2 orbit transfer, and its size (∼ 200 pc radius) coincides with the extraordinary reservoir of dense molecular clouds in the inner bulge, the Central Molecular Zone (CMZ). We also present some results from our preliminary simulations for gas transportation from the CMZ to the circumnuclear disk of molecular clouds located at a few parsecs from the GC.