Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-Forming Galaxies. (arXiv:2002.08964v1 [astro-ph.GA])

Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-Forming Galaxies. (arXiv:2002.08964v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sun_J/0/1/0/all/0/1">Jiayi Sun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leroy_A/0/1/0/all/0/1">Adam K. Leroy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ostriker_E/0/1/0/all/0/1">Eve C. Ostriker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hughes_A/0/1/0/all/0/1">Annie Hughes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosolowsky_E/0/1/0/all/0/1">Erik Rosolowsky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schruba_A/0/1/0/all/0/1">Andreas Schruba</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schinnerer_E/0/1/0/all/0/1">Eva Schinnerer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Blanc_G/0/1/0/all/0/1">Guillermo A. Blanc</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Faesi_C/0/1/0/all/0/1">Christopher Faesi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kruijssen_J/0/1/0/all/0/1">J. M. Diederik Kruijssen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meidt_S/0/1/0/all/0/1">Sharon Meidt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Utomo_D/0/1/0/all/0/1">Dyas Utomo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bigiel_F/0/1/0/all/0/1">Frank Bigiel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bolatto_A/0/1/0/all/0/1">Alberto D. Bolatto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chevance_M/0/1/0/all/0/1">Mélanie Chevance</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chiang_I/0/1/0/all/0/1">I-Da Chiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dale_D/0/1/0/all/0/1">Daniel Dale</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Emsellem_E/0/1/0/all/0/1">Eric Emsellem</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Glover_S/0/1/0/all/0/1">Simon C. O. Glover</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grasha_K/0/1/0/all/0/1">Kathryn Grasha</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Henshaw_J/0/1/0/all/0/1">Jonathan Henshaw</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Herrera_C/0/1/0/all/0/1">Cinthya N. Herrera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jimenez_Donaire_M/0/1/0/all/0/1">Maria Jesus Jimenez-Donaire</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_J/0/1/0/all/0/1">Janice C. Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pety_J/0/1/0/all/0/1">Jérôme Pety</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Querejeta_M/0/1/0/all/0/1">Miguel Querejeta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saito_T/0/1/0/all/0/1">Toshiki Saito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sandstrom_K/0/1/0/all/0/1">Karin Sandstrom</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Usero_A/0/1/0/all/0/1">Antonio Usero</a>

We compare the observed turbulent pressure in molecular gas,
$P_mathrm{turb}$, to the required pressure for the interstellar gas to stay in
equilibrium in the gravitational potential of a galaxy, $P_mathrm{DE}$. 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
$P_mathrm{turb}$ correlates with, but almost always exceeds the estimated
$P_mathrm{DE}$ 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 $P_mathrm{DE}$ on cloud scales, which accounts for
molecular gas self-gravity, external gravity, and ambient pressure, agrees well
with the observed $P_mathrm{turb}$ in galaxy disks. We also find that
molecular gas with cloud-scale
${P_mathrm{turb}}approx{P_mathrm{DE}}gtrsim{10^5,k_mathrm{B},mathrm{K,cm^{-3}}}$
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 $P_mathrm{turb}$ and the observed
SFR surface density, $Sigma_mathrm{SFR}$, 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 $Sigma_mathrm{SFR}$ and kpc-scale $P_mathrm{DE}$ 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 $P_mathrm{DE}$ reported in previous works.

http://arxiv.org/icons/sfx.gif