Gas Content and Kinematics in Clumpy, Turbulent Star-forming Disks

Abstract

We present molecular gas mass estimates for a sample of 13 local galaxies whose kinematic and star forming properties closely resemble those observed in $z\approx 1.5$ main-sequence galaxies. Plateau de Bure observations of the CO[1-0] emission line and Herschel Space Observatory observations of the dust emission both suggest molecular gas mass fractions of ~20%. Moreover, dust emission modeling finds $T_{dust}<$30K, suggesting a cold dust distribution compared to their high infrared luminosity. The gas mass estimates argue that $z\sim$0.1 DYNAMO galaxies not only share similar kinematic properties with high-z disks, but they are also similarly rich in molecular material. Pairing the gas mass fractions with existing kinematics reveals a linear relationship between $f_{gas}$ and $\sigma$/$v_c$, consistent with predictions from stability theory of a self-gravitating disk. It thus follows that high gas velocity dispersions are a natural consequence of large gas fractions. We also find that the systems with lowest depletion times ($\sim$0.5 Gyr) have the highest ratios of $\sigma$/$v_c$ and more pronounced clumps, even at the same high molecular gas fraction.

10 pages, 6 figures. Accepted to ApJ

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Cited by in corpus (8)

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• Spiral-arm instability: giant clump formation via fragmentation of a galactic spiral arm
• The connection between the peaks in velocity dispersion and star-forming clumps of turbulent galaxies
• Angular momentum of $z\sim 1.5$ galaxies and their local analogues with adaptive optics
• Giant Star Forming Complexes in High-z Main Sequence Galaxy Analogues: The Internal Structure of Clumps in DYNAMO Galaxies
• Stellar Masses of Clumps in Gas-rich, Turbulent Disk Galaxies
• CO Excitation in High-z Main Sequence Analogues: Resolved CO(4-3)/CO(3-2) Line Ratios in DYNAMO Galaxies
• Size-scaling of clump instabilities in turbulent, feedback regulated disks