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Journal Articles The Astrophysical Journal Year : 2020

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

Jiayi Sun
Adam K. Leroy
  • Function : Author
Eve C. Ostriker
  • Function : Author
Erik Rosolowsky
Andreas Schruba
  • Function : Author
Eva Schinnerer
Guillermo A. Blanc
  • Function : Author
Christopher Faesi
J. M. Diederik Kruijssen
  • Function : Author
Sharon Meidt
Dyas Utomo
Frank Bigiel
Alberto D. Bolatto
  • Function : Author
Mélanie Chevance
I-Da Chiang
Daniel Dale
Simon C. O. Glover
  • Function : Author
Kathryn Grasha
Jonathan Henshaw
Cinthya N. Herrera
  • Function : Author
Maria Jesus Jimenez-Donaire
  • Function : Author
Janice C. Lee
  • Function : Author
Jérôme Pety
Miguel Querejeta
Toshiki Saito
Karin Sandstrom
Antonio Usero

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 multiwavelength data that trace 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 overpressurized relative to the large-scale environment. We show that this overpressurization 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 ≳ 105 kB K cm-3 in our sample is more likely to be self-gravitating, whereas gas at lower pressure it 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 galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale PDE reported in previous works.

Dates and versions

insu-03673157 , version 1 (19-05-2022)

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Jiayi Sun, Adam K. Leroy, Eve C. Ostriker, Annie Hughes, Erik Rosolowsky, et al.. Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies. The Astrophysical Journal, 2020, 892, ⟨10.3847/1538-4357/ab781c⟩. ⟨insu-03673157⟩
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