Self Gravity and Physical State of Molecular Gas in Nearby Galaxies

We aim to understand the structural and dynamical properties of molecular interstellar medium (ISM) across galaxies, the impact of its physical state on star formation, and how galactic environments set this state. I will show key results from PHANGS, the first large ALMA survey of molecular ISM resolving down to ``cloud scale'' (1'' ~ 50-100 pc resolution) across large areas in star forming galaxies. Combining PHANGS and earlier Local Group surveys, we make fundamental structural measurements across an unprecedented sample of 15 galaxies. We find strong correlations between molecular gas velocity dispersion and surface density, which suggest a prevailing self-gravity dominated state in the molecular ISM in star forming galaxies. We also find evidence for environmental dependence of gas physical state. Combining these results with local star formation rate measurements for the galaxy M51, we find the strength of self-gravity a good predictor of molecular gas depletion time, with more strongly bound gas structures form star at higher (normalized) rate.

Jiayi Sun(graduate student, Ohio State University)
1st Seminar Room, KIAA-PKU
Friday, July 7, 2017 - 5:00pm