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 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 photoionised 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 over-pressured, 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% 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.

Molecular Cloud Populations in the Context of Their Host Galaxy Environments: A Multiwavelength Perspective

“…Our rich multiwavelength measurements have already supported multiple observational studies on PHANGS galaxies. These studies cover a broad range of topics, including the dynamical equilibrium of the ISM (Sun et al 2020b), pressures in H ii regions (Barnes et al 2021), morphological features in the stellar disks (Querejeta et al 2021), nuclear gas outflows (Stuber et al 2021), and the molecular gas-star formation cycle (Pan et al 2022). We also expect similar applications in future studies on PHANGS targets examining molecular cloud lifecycle (J.…”

“…In this way, we assemble the diverse set of observational data described in Section 2 into a coherent, multiwavelength database. An early version of this database was constructed by Sun et al (2020b), with its subsequently improved versions used in several publications (e.g., Herrera et al 2020;Jeffreson et al 2020;Barnes et al 2021;Querejeta et al 2021;Stuber et al 2021). The source code for database construction, including generic tools for aggregating measurements from maps and catalogs into the existing database, is available on GitHub 6 , and a copy of the version used in this article is published on Zenodo (Sun 2022).…”

“…These high-level data products have already been used in a number of studies. Herrera et al (2020) and Barnes et al (2021) have utilized previous versions of these tables to quantitatively assess several physical mechanisms relevant to molecular cloud and H ii region evolution, including stellar feedback and pressure balance. Several ongoing works also rely on these tables to calculate the star formation efficiency and its link to small-scale turbulence, orbital shear, and disk instabilities (E. Rosolowsky et al in preparation; J.…”

The evolution of protoplanetary discs in star formation and feedback simulations

“…The feedback in the models considers photoionisation (which is generally thought to be the dominant feedback mechanism in H regions prior to supernovae, e.g. Dale et al 2014;Geen et al 2020;Barnes et al 2021) and radiation pressure but not winds or protostellar jets (the latter of which can be important prior to the formation of massive stars Grudić et al 2022). Note that the radiation pressure force is calculated using both the contributions from dust and gas (through H/He absorption and electron scattering) and that the dust and gas are dynamically coupled in these models.…”