PHYSICAL PROPERTIES OF MOLECULAR CLOUDS FOR THE ENTIRE MILKY WAY DISK

• Published in: The Astrophysical journal Vol. 834; no. 1; pp. 57 - 87
• Main Authors: Miville-Deschênes, Marc-Antoine, Murray, Norman, Lee, Eve J.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-01-2017; IOP Publishing
• Subjects: Accretion disks; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AUGMENTATION; CARBON MONOXIDE; Clouds; Correlation; CORRELATIONS; COSMIC DUST; DATA ANALYSIS; DENSITY; Dispersion; DISPERSIONS; DISTANCE; EMISSION; Galactic disk; Galaxies; Galaxy: general; HYDROGEN; Injection; ISM: clouds; ISM: general; ISM: kinematics and dynamics; LINE WIDTHS; MASS; methods: data analysis; MILKY WAY; Molecular clouds; Physical properties; TURBULENCE; Turbulent energy; VELOCITY
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/834/1/57

ABSTRACT This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the 12CO emission observed within . The catalog was produced using a hierarchical cluster identification method applied to the result of a Gaussian decomposition of the Dame et al. data. The total H2 mass in the catalog is , in agreement with previous estimates. We find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. The most probable cloud size is pc. We find that , with no correlation between the cloud surface density, , and R. In contrast with the general idea, we find a rather large range of values of , from 2 to 300 M pc−2, and a systematic decrease with increasing Galactic radius, . The cloud velocity dispersion and the normalization both decrease systematically with . When studied over the whole Galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between and . The normalization of this correlation is constant to better than a factor of two for . This relation is used to disentangle the ambiguity between near and far kinematic distances. We report a strong variation of the turbulent energy injection rate. In the outer Galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner Galaxy.