Ammonia Thermometry, Water and Methanol Masers in Star Forming Galaxies
Thursday March 23, 2017
|Presenter:||Mark Gorski (UNM)|
|Series:||Center for Astrophysics Research and Technologies Seminar Series|
We present Karl G Jansky Very Large Array (VLA) molecular line observations of the nearby star forming galaxies NGC 253, IC 342, NGC 6946, and NGC 2146. These galaxies span a range of ecosystems and star formation rates from Milky Way like (~1Mʘ) to starbursts (~10Mʘ), and are close enough to be resolved with a few tens of pc resolution with the VLA. At this resolution we are well matched to the physical scales of Giant Molecular Clouds (GMCs) and therefore sensitive to the dominant processes therein. We have selected metastable inversion transitions of NH3 from (1,1) to (5,5) and the (9,9), the 22.2 GHz H2O (616-523) maser, and the 36.1 GHz CH3OH (4-14-303) maser. Using the NH3 molecule as a temperature probe, we are able to expose the heating and cooling balance of the dense molecular gas in these galaxies. Our results suggest no dominant heating mechanism in the nearby starburst galaxy NGC 253. The selected masers lines are collisionally pumped and reveal the locations of shocked material. We report the discovery of H2O masers associated with the large-scale biconical outflow for the first time, indicating the presence of shocked dense gas. Finally, we present the first measurements of resolved extragalactic CH3OH masers.
|Location:||Room 190, Physics & Astronomy|