Comparing the pre-SNe feedback and environmental pressures for 6000 HII
  regions across 19 nearby spiral galaxies
  The feedback from young stars (i.e. pre-supernova) is thought to play a
crucial role in molecular cloud destruction. In this paper, we assess the
feedback mechanisms acting within a sample of 5810 HII regions identified from
the PHANGS-MUSE survey of 19 nearby ($<$ 20 Mpc) star-forming, main sequence
spiral galaxies (log($M_\star$/M$_\odot$)= 9.4 $-$ 11). These optical
spectroscopic maps are essential to constrain the physical properties of the
HII regions, which we use to investigate their internal pressure terms. We
estimate the photoionised gas ($P_\mathrm{therm}$), direct radiation
($P_\mathrm{rad}$), and mechanical wind pressure ($P_\mathrm{wind}$), which we
compare to the confining pressure of their host environment ($P_\mathrm{de}$).
The HII regions remain unresolved within our ${\sim}50{-}100$ pc resolution
observations, so we place upper ($P_\mathrm{max}$) and lower ($P_\mathrm{min}$)
limits on each of the pressures by using a minimum (i.e. clumpy structure) and
maximum (i.e. smooth structure) size, respectively. We find that the
$P_\mathrm{max}$ measurements are broadly similar, and for $P_\mathrm{min}$ the
$P_\mathrm{therm}$ is mildly dominant. We find that the majority of HII regions
are over-pressured, $P_\mathrm{tot}/P_\mathrm{de} =
(P_\mathrm{therm}+P_\mathrm{wind}+P_\mathrm{rad})/P_\mathrm{de} > 1$, and
expanding, yet there is a small sample of compact HII regions with
$P_\mathrm{tot,max}/P_\mathrm{de} < 1$ ($\sim$1% of the sample). These mostly
reside in galaxy centres ($R_\mathrm{gal}<1$kpc), or, specifically,
environments of high gas surface density;
log($\Sigma_\mathrm{gas}/\mathrm{M_\odot} \mathrm{pc}^{-2}$)$\sim$2.5 (measured
on kpc-scales). Lastly, we compare to a sample of literature measurements for
$P_\mathrm{therm}$ and $P_\mathrm{rad}$ to investigate how dominant pressure
term transitions over around 5dex in spatial dynamic range and 10 dex in
pressure.
