|Time:||星期五, 12月 13, 2019, 10:30am|
|Title:||Demographics and Environment-dependence of Molecular Cloud Properties in Nearby Star-forming Galaxies (informal talk)|
|Speaker:||Mr. Jiayi Sun (Ohio State Univ.)|
I will show key results from the PHANGS-ALMA survey, an ALMA large program obtaining arcsecond resolution CO imaging of ∼90 nearby, star-forming galaxies. With linear resolution (~60-120 pc) reaching the size of individual giant molecular clouds (GMCs), PHANGS-ALMA provides the most complete atlas ever of GMCs in the local star-forming galaxy population. In the full PHANGS-ALMA sample, we see a wide range of molecular gas surface density, velocity dispersion, and turbulent pressure on 60-120 pc scales (i.e., "cloud scales"). These properties show clear dependence on the large-scale galactic environment. We find that the internal pressure in molecular gas almost always exceeds the large-scale average ISM pressure. We show that this overpressurization results because molecular gas self-gravity significantly alters the local gravitational potential on cloud scales. In many cases, self-gravity outweighs external gravity and ambient pressure combined. Overall, the scaling between ISM pressure and local star formation rate agree well with predictions from self-regulated star formation models.
Host: Prof. Dandan Xu