A1 Refereed original research article in a scientific journal
Masses, Star Formation Efficiencies, and Dynamical Evolution of 18,000 H ii Regions
Authors: Pathak, Debosmita; Leroy, Adam K.; Barnes, Ashley. T.; Thompson, Todd A.; Lopez, Laura A.; Sandstrom, Karin M.; Sun, Jiayi; Glover, Simon C. O.; Klessen, Ralf S.; Koch, Eric W.; Larson, Kirsten L.; Lee, Janice; Meidt, Sharon; Sanchez-Blazquez, Patricia; Schinnerer, Eva; Bazzi, Zein; Belfiore, Francesco; Boquien, Médéric; Chown, Ryan; Colombo, Dario; Congiu, Enrico; Egorov, Oleg V.; Eibensteiner, Cosima; Kurapati, Sushma; Querejeta, Miguel; Dale, Daniel A.; Kravtsov, Timo; Padave, Mansi; Pisano, D. J.; Rosolowsky, Erik; Sarbadhicary, Sumit K.; Williams, Thomas G.; Indebetouw, Remy; Pan, Hsi-An; Ubeda, Leonardo; Amiri, Amirnezam; Bigiel, Frank; Blanc, Guillermo A.; Grasha, Kathryn
Publisher: Institute of Physics Publishing
Publication year: 2025
Journal: Astrophysical Journal Letters
Article number: L20
Volume: 993
Issue: 1
ISSN: 2041-8205
eISSN: 2041-8213
DOI: https://doi.org/10.3847/2041-8213/ae0e70
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Open Access publication channel
Web address : https://iopscience.iop.org/article/10.3847/2041-8213/ae0e70
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/505489513
We present measurements of the masses associated with ∼18,000 H ii regions across 19 nearby star-forming galaxies by combining data from JWST, Hubble Space Telescope, MUSE, Atacama Large Millimeter/submillimeter Array, Very Large Array, and MeerKAT from the multiwavelength PHANGS survey. We report 10 pc-scale measurements of the mass of young stars, ionized gas, and older disk stars coincident with each H ii region, as well as the initial and current mass of molecular gas, atomic gas, and swept-up shell material, estimated from lower-resolution data. We find that the mass of older stars dominates over young stars at ≳10 pc scales, and ionized gas exceeds the stellar mass in most optically bright H ii regions. Combining our mass measurements for a statistically large sample of H ii regions, we derive 10 pc-scale star formation efficiencies of ≈6%–17% for individual H ii regions. Comparing each region’s self-gravity with the ambient interstellar medium (ISM) pressure and total pressure from presupernova stellar feedback, we show that most optically bright H ii regions are overpressured relative to their own self-gravity and the ambient ISM pressure and that they are hence likely expanding into their surroundings. Larger H ii regions in galaxy centers approach dynamical equilibrium. The self-gravity of regions is expected to dominate over presupernova stellar feedback pressure at ≳130 and 60 pc scales in galaxy disks and centers, respectively, but is always subdominant to the ambient ISM pressure on H ii region scales. Our measurements have direct implications for the dynamical evolution of star-forming regions and the efficiency of stellar feedback in ionizing and clearing cold gas.
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Funding information in the publication:
D.P. is supported by the NSF GRFP.
A.K.L. and D.P. gratefully acknowledge support from NSF AST AWD 2205628, JWST-GO-02107.009-A, and JWST-GO-03707.001-A. A.K.L. also gratefully acknowledges support by a Humbolt Research Award.
L.A.L. acknowledges support through the Heising-Simons Foundation grant 2022-3533.
J.S. acknowledges support by the National Aeronautics and Space Administration (NASA) through the NASA Hubble Fellowship grant HST-HF2-51544 awarded by the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under contract NAS 5-26555.
D.J.P. greatly acknowledges support from the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation.
M.B. acknowledges support from the ANID BASAL project FB210003. This work was supported by the French government through the France 2030 investment plan managed by the National Research Agency (ANR), as part of the Initiative of Excellence of Université Côte d’Azur under reference number ANR-15-IDEX-01.
Z.B. and D.C. gratefully acknowledge the Collaborative Research Center 1601 (SFB 1601 subproject B3) funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 500700252. D.C. acknowledges support by the Deutsche Forschungsgemeinschaft, DFG project number SFB 956-A3.
K.G. is supported by the Australian Research Council through the Discovery Early Career Researcher Award (DECRA) Fellowship (project number DE220100766) funded by the Australian Government.
E.R. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), funding reference number RGPIN-2022-03499, and support from the Canadian Space Agency, funding reference 23JWGO2A07.
O.E. acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—project ID 541068876.
P.S.B. acknowledges support from the Spanish grant PID2022-138855NB-C31, funded by MCIN/AEI/10.13039/501100011033/FEDER, EU.
R.S.K. acknowledges financial support from the ERC via Synergy Grant “ECOGAL” (project ID 855130), from the German Excellence Strategy via the Heidelberg Cluster “STRUCTURES” (EXC 2181—390900948), and from the German Ministry for Economic Affairs and Climate Action in project “MAINN” (funding ID 50OO2206).
