The Galactic Nuclear Wind and the CO Disk

Based on the MWISP survey, we study high-z CO emission toward the tangent points, in which the distances of the molecular clouds (MCs) are well determined. In the region of l = 12°--26° and |b| < 5°, a total of 321 MCs with |z|>110 pc are identified, of which nearly 30 extreme high-z MCs (EHMCs at |z|> 260 pc) are concentrated in a very narrow region of R_GC = 2.6--3.1 kpc. The EHMC concentrations, together with other high-z MCs constitute molecular crater-wall structures surrounding the edges of the HI voids that are physically associated with the Fermi bubbles.

Intriguingly, some large high-z MCs, which lie in the crater walls above and below the Galactic plane, show cometary structures with the head toward the plane, favoring the scenario that the entrained molecular gas moves with the multi-phase flows from the plane to the high-z regions. We suggest that the Milky Way nuclear wind has a significant impact on the Galactic gaseous disk. The powerful nuclear wind at 3--6 Myr ago is likely responsible for the observational features: (1) the enhanced CO gas lying in the edges of the HI voids, (2) the deficiency of atomic and molecular gas within R_GC=3 kpc, (3) the possible connection between the EHMC concentrations and the 3 kpc arm, and (4) the elongated high-z MCs with the tail pointing away from the Galactic plane.

Yang Su (PMO)
Zoom Link: Meeting ID: 853 6748 1924 Passcode: 804585
Ke Wang
Thursday, September 8, 2022 - 3:30PM to Thursday, September 8, 2022 - 4:30PM
Dr. Yang Su received his Ph.D. from the Nanjing University in 2007. He currently works at the Purple Mountain Observatory, Chinese Academy of Sciences. He is the main member of the MWISP group (i.e., the large-scale survey of molecular clouds along the northern Galactic plane). Dr. Yang Su does research in properties of atomic gas, molecular gas, and feedback from massive stars. His research interests also include the structure and evolution of the Milky Way, and the structure of the ISM (i.e., the atomic gas + molecular gas in radio emission, dust emission of the gas, and the high-energy emission in X-ray and TeV bands). He recently discovered that there is substantial molecular gas blown away by the Milky Way nuclear wind using the large CO samples from the MWISP project.