Studies of molecular clouds at the centre of the Milky Way Galaxy

by Roland Karlsson (SU Astronomy)

Friday 4 Mar 2016, 10:30 → 11:30 Europe/Stockholm

FC61

I have studied neutral molecular clouds at the innermost 50 light years from the Galactic centre (GC) with the Karl Jansky Very Large Array (VLA) in New Mexico, USA, and with data from observations with the Swedish-ESO Submillimetre Telescope (SEST) in Chile, and also from the Odin orbital observatory. I have detected a new stream-like feature of gas that seems to link the previously known central ring of gas clouds (the CircumNuclear Disk - CND) and the inner region immediately surrounding the supermassive black hole located at the GC. Moreover, the hypothesis of feeding the CND from outside clouds is supported by this work. Contemporary discussions in the literature - that the central bar structure of the Galaxy would act as a pump of material inwards from the spiral arms towards the GC via a hierarchical structure of molecular clouds - are also suggested by the data. A number of OH-maser sources have been observed and some of those are shown to reside at shock fronts or anticipated regions of collisions between molecular clouds or at star formation regions. Unusually high water abundance was detected by Odin at the south-west part of the CND, indicative of shocks and strong turbulence. Moreover, I have produced high-resolution spectral line maps of OH absorption intensity in the four main transition lines of OH at 1612, 1665, 1667 and 1720 MHz, as well as apparent opacity and position-velocity maps of the GC region.