Comparing the pre-SNe feedback and environmental pressures for 6000 H iiregions 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) starforming, 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.

HII regions in CALIFA survey: II. The relation between their physical properties and galaxy evolution

“…On the other hand, for the electron density, the results suggest that regions with higher dust extinction (i.e., corresponding to large gas densities Brinchmann et al 2004;Barrera-Ballesteros et al 2020) do have larger n 𝑒 too. This would imply that their internal pressure should be also higher, in agreement with the trends recently reported by Barnes et al (2021). In this case, since 𝑈 depends inversely on the electron density the trend observed for this parameter could be a combination of the trends reported for both O/H and 𝑛 𝑒 .…”

“…The local pressure may also play a role in this regards, in addition to the direct effect of the metal content. Radial declines in the pressure are suggested based on the relations proposed by Barrera-Ballesteros et al (2021a) and the direct estimations reported by Barnes et al (2021). A high pressure may facilitate the fragmentation and collapse of smaller molecular clouds and the formation of lower surface brightness H regions.…”

“…This result is expected since at the central regions of the galaxies, with larger values of the stellar and molecular gas surface densities, the pressure is expected to be larger (e.g. Barrera-Ballesteros et al 2021a; Barnes et al 2021). Then the density declines and rise again in the outer regions.…”

“…The H region catalogs produced by these surveys are based on large samples of galaxies covering a wide range of morphological types (Sánchez et al 2012b(Sánchez et al , 2013. Significant results have been determined using these catalogs: (i) the existence of a typical abundance gradient (Sánchez et al 2014(Sánchez et al , 2015aSánchez-Menguiano et al 2018), (ii) the deviations from this radial abundance gradient induced by spiral arms (Sánchez-Menguiano et al 2020) and their azimuthal variations (Vogt et al 2017), (iii) the correlation between the oxygen abundance of H regions and the stellar mass densities of underlying stellar populations (Rosales-Ortega et al 2012;Barrera-Ballesteros et al 2016), (iv) the existence of average patterns in the radial gradient of different physical properties (Sánchez et al 2012b), (v) the existence of a large number of H regions contaminated by supernovae remnants (Cid Fernandes et al 2021), (vi) chemical evolution models at kpc scales (Barrera-Ballesteros et al 2018), and (vii) the comparison between the pre-SNe feedback and environmental pressure across the optical extension of spiral galaxies (Barnes et al 2021), among the most important ones.…”

The Gas-Star Formation Cycle in Nearby Star-forming Galaxies II. Resolved Distributions of CO and H$α$ Emission for 49 PHANGS Galaxies

“…This breakdown of the scaling relation has been attributed to the evolution of GMCs (Schruba et al 2010;Feldmann et al 2011;Kruijssen & Longmore 2014). The separation between GMCs and star formation tracers is now regularly used as an empirical probe of the cycle between gas and star formation (Kawamura et al 2009;Schruba et al 2010;Kruijssen & Longmore 2014;Kruijssen et al 2018), including the timescale of evolutionary cycling between GMCs and star formation (Kruijssen et al 2019;Chevance et al 2020;Kim et al 2021) and the impact of destructive stellar feedback (e.g., photoionization, stellar winds, and supernova explosions) on the structure of interstellar medium (ISM) and future star formation (Barnes et al 2020(Barnes et al , 2021Chevance et al 2022).…”