2021MNRAS.508.5362B

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 H II regions identified from the PHANGS-MUSE survey of 19 nearby (<20 Mpc) star-forming, main-sequence spiral galaxies [log(M_*/M_☉) = 9.4-11]. These optical spectroscopic maps are essential to constrain the physical properties of the H II regions, which we use to investigate their internal pressure terms. We estimate the photoionized gas (P_therm), direct radiation (P_rad), and mechanical wind pressure (P_wind), which we compare to the confining pressure of their host environment (P_de). The H II regions remain unresolved within our ∼50-100 pc resolution observations, so we place upper (P_max) and lower (P_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_max measurements are broadly similar, and for P_min the P_therm is mildly dominant. We find that the majority of H II regions are overpressured, P_tot/P_de = (P_therm + P_wind + P_rad)/P_de > 1, and expanding, yet there is a small sample of compact H II regions with P_tot,max/P_de < 1 (∼1 per cent of the sample). These mostly reside in galaxy centres (R_gal < 1 kpc), or, specifically, environments of high gas surface density; log(Σ_gas/M_☉ pc^–2) ∼ 2.5 (measured on kpc-scales). Lastly, we compare to a sample of literature measurements for P_therm and P_rad to investigate how dominant pressure term transitions over around 5 dex in spatial dynamic range and 10 dex in pressure.