The Galactic dynamics revealed by the filamentary structure in the atomic hydrogen emission

Juan D. Soler

Tuesday, Dec. 6th, 15:50CET

We present a study of the filamentary structure in the neutral atomic hydrogen (HI) emission at 21 cm using the HI4PI and The HI/OH/Recombination-line (THOR) surveys of the Galactic plane. We found that the Milky Way’s disk regions beyond ten kiloparsecs and up to roughly 18 kiloparsecs from the Galactic center display HI filamentary structures predominantly parallel to the Galactic plane. However, we found that the HI filaments are mostly perpendicular or do not have a preferred orientation with respect to the Galactic plane for regions at lower Galactocentric radii. We interpret these results as the imprint of supernova feedback in the inner Galaxy and Galactic rotation and shear in the outer Milky Way. We also studied the carbon monoxide (CO) emission observations from The Milky Way Imaging Scroll Painting (MWISP) survey. We found that the orientations of the filamentary structures traced by CO emission differ from those in the HI emission. We consider this to indicate that the molecular structures do not simply inherit these properties from parental atomic clouds. Instead, they are shaped by local physical conditions, such as stellar feedback, magnetic fields, and Galactic spiral shocks.