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2017 Hot Sci @ STScI

Mapping ISM flows in the Milky Way with kinetic tomography

Presented by: Kirill Tchernyshyov  (JHU)
Category: Science Colloquia   Duration: 30 minutes   Broadcast date: August 30, 2017
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There is general agreement that the ISM of the Milky Way is arranged into a spiral-like pattern of some sort, though there is not yet agreement on how regular this spiral-like pattern is or how it evolves. To investigate this and other questions relating to flows of interstellar matter in the Galaxy, we have developed a suite of techniques, known collectively as Kinetic Tomography, for deriving maps of line-of-sight velocity as a function of three-dimensional position. These techniques produce maps that are qualitatively consistent with each other despite being based on entirely disjoint combinations of dust reddening, gas emission, and gas absorption observations. As an additional check, we have confirmed that the velocities these maps assign to the 3D positions of high mass star formation regions agree with the regions' actual measured velocities. We have compared these maps with predictions from the two main theories for the Milky Way's spiral structure -- the quasi-stationary spiral shock model and the dynamic or material spiral structure model. The maps are clearly inconsistent with a quasi-stationary spiral shock and somewhat inconsistent with dynamic/material spiral structure.