Colloquium on Mar. 20, 2025

Disc instability and angular momentum transfer driven by a decelerating bar

Speaker: Chengdong Li (NJU)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Mar. 20, 2025

Abstract:

The bar plays an important role in shaping both the dark matter and baryonic distribution in the Milky Way. The long bar of the Galaxy is believed to slow down due to the dynamical friction with the dark matter halo and the disc. We use an axisymmetric background potential plus a central bar model to perform the test particle simulations in order to investigate the influence of a decelerating bar on the disc instability and the angular momentum transfer to the disc. We show that the decelerating bar can produce two-armed phase space spirals in both short- and long-term evolutions. We also show that the bar is responsible to the rotations of the bulge and inner halo measured by the Gaia data through the angular momentum transfer caused by the dynamical friction. In addition, the decelerating bar can bring the bulge stars outwards via the co-rotation trapped which contributes the origin of the thin-disc-like low-metallicity stars (VMPs). As a conclusion, the central bar is crucial in Galaxy evolution by shaping the disc instability and the angular momentum re-distribution.

Report PPT:  SWIFAR_Chengdong Li.pdf