Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies

Date

2020

Authors

Sun, Jiayi
Leroy, Adam K
Ostriker, Eve C
Hughes, Annie
Rosolowsky, Erik W
Schruba, Andreas
Schinnerer, Eva
Blanc, Guillermo A
Faesi, Christopher M
Kruijssen, J M Diederik

Journal Title

Journal ISSN

Volume Title

Publisher

IOP Publishing

Abstract

We compare the observed turbulent pressure in molecular gas, Pturb, to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, PDE. To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multi-wavelength data that traces the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that Pturb correlates with, but almost always exceeds the estimated PDE on kiloparsec scales. This indicates that the molecular gas is over-pressurized relative to the large-scale environment. We show that this over-pressurization can be explained by the clumpy nature of molecular gas; a revised estimate of PDE on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed Pturb in galaxy disks. We also find that molecular gas with cloud-scale Pturb≈PDE≳105kBKcm−3 in our sample is more likely to be self-gravitating, whereas gas at lower pressure appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between Pturb and the observed SFR surface density, ΣSFR, is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between ΣSFR and kpc-scale PDE in gala

Description

Keywords

Interstellar molecules, Star formation, Interstellar dynamics

Citation

Source

The Astrophysical Journal

Type

Journal article

Book Title

Entity type

Access Statement

Open Access

License Rights

DOI

10.3847/1538-4357/ab781c

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