The Distribution of [CII] 158 μm emission in the Milky Way revealed by Herschel HIFI
William, D. Langer, T. Velusamy, and P.F. Goldsmith
We present for the first time position-velocity maps of the distribution of the [CII] 158 micron emission over a volume-weighted sample of the entire galactic disk of the Milky Way. These observations are part of the Herschel Open Time Key Project Galactic Observations of Terahertz C+ (GOTC+), a survey devoted to study the [CII] 158 micron line over different conditions in the Galactic plane with the Herschel HIFI instrument. Together with supplementary HI and CO surveys, the [CII] emission reveals the distribution of the warm and cold neutral medium, “Dark H2 Gas”, dense photon dominated regions, and molecular clouds over the entire galactic disk with b=0, ±0.5, and ±1.0 degrees. The [CII], HI, and CO position velocity maps allow us to estimate the mass fraction of gas in these phases of the ISM, as well as to map the distribution of the thermal pressures and far-ultraviolet radiation field. These observations will have a crucial impact on our understanding of the interstellar medium and the structure of the Galaxy. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.