EPoS Contribution
EPoS Contribution
Dense Gas in Giant Molecular Filaments: Connecting the Milky Way to other Galaxies

Yuan Wang
MPIA, Heidelberg, DE
While extragalactic molecular gas surveys imply a connection between star formation properties, global cloud and environmental parameters, empirical evidence shows that star formation in the Milky Way is related to the high density material in the molecular clouds (MCs), and suggests a "universal" column or volume density threshold for star formation in local clouds and typical spiral galaxies. We present a pilot study of the dynamics of the dense gas of an entire Giant Molecular Filaments (GMF54), which is an analog to the objects dominating typical extragalactic observations. We mapped the dense gas of GMF54 (~45pc) with the IRAM 30m telescope, covering the 1-0 transition of the common dense gas tracers HCN, HNC, HCO+ and their 13C isotopologue molecules, as well as the cold dense gas tracer N2H+. We will present the dense gas fraction, the line ratios and the probability density function (PDFs) for the molecular column densities of the filament. Furthermore, we connect the line ratios with the PDFs, and compare with the extragalactic observations. Our results provide the crucial "sub-beam" density distribution of material within clouds for the extragalactic studies.
Caption: The GRS (Jackson et al. 2006) 13CO(1-0), HCO+(1-0), HCN(1-0) and N2H+(1-0) integrated intensity contours overlaid on the Hi-GAL 500 micron map (Molinari et al. 2016). The FWHM beam size of each contour image is shown at the bottom left corner. The contour levels in each panel are 3, 6, 18, and 30 σ. The ellipses in the HCN(1-0) panel mark the components which are at a different distance from the giant filament.
Collaborators:
H. Beuther, MPIA, DE
S. Meidt, MPIA, DE
J. Kainulainen, OSO, SE
S. Ragan, Cardiff U, GB
J. Mottram, MPIA, DE
J. Soler, MPIA, DE
H. Linz, MPIA, DE
F. Bigiel, ZAH, DE
E. Schinnerer, MPIA, DE
T. Henning, MPIA, DE
Suggested Session: Molecular clouds