Gas Transfer between the Inner 3 kpc Disk and the Galactic Central Molecular Zone

作者：Yang Su, Shiyu Zhang, Yan Sun, Ji Yang, Fujun Du, Min Fang, QING-ZENG YAN, Shaobo Zhang, Zhiwei Chen, Xuepeng Chen, Xin Zhou, Lixia Yuan, Yuehui Ma · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/adc38e · 被引用次数：4 · 研究领域：Astrophysics and Star Formation Studies、Stellar, planetary, and galactic studies、Astrophysical Phenomena and Observations

Abstract We uncovered a more tilted molecular gas structure with highly negative velocities located near the dust lane. Our observations show that the approaching gas flows from the overshoot process are captured by the gravitational potential of the bar and then flow toward the Galactic central molecular zone (CMZ) through the bar channel. The recycled gas from the overshoot effect, in conjunction with freshly accreted gas from the inner 3 kpc disk, accumulates significantly near the R GC ∼ 1 2 R bar and R GC ∼ 2 3 R bar regions by adopting a bar length of ∼3.2–3.4 kpc. Importantly, within these regions, there are frequent collisions and substantial angular momentum exchanges between gas flows with different trajectories. In this scenario, the dissipation processes arising from interactions between colliding flows, together with the varying torques induced by the nonaxisymmetric bar, effectively transfer the angular momentum of viscous gas outward, thereby driving the molecular gas to settle into the CMZ within about three orbital periods. A long-term gas inflow with an average rate of ≳1.1 M ⊙ yr −1 , coupled with intense transient accretion events that exceed the average rate by several times due to the overshoot effect, significantly regulates the gas distribution, physical properties, and dynamical evolution of the CMZ. These new findings provide robust observation...