Comparing the pre-SNe feedback and environmental pressures for 6000 HII regions across 19 nearby spiral galaxies

Abstract

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 (<20Mpc) star-forming, main-sequence spiral galaxies [log(M-star/M-circle dot) = 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 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 Hii regions remain unresolved within our similar to 50-100pc 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 Hii 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 Hii regions with P-tot,P-max/P-de < 1 (similar to 1 per cent of the sample). These mostly reside in galaxy centres (R-gal < 1kpc), or, specifically, environments of high gas surface density; log(Sigma(gas)/M(circle dot)pc(-2)) similar to 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 5dex in spatial dynamic range and 10dex in pressure.