PHANGS-JWST First Results: Tracing the Diffuse Interstellar Medium with JWST Imaging of Polycyclic Aromatic Hydrocarbon Emission in Nearby Galaxies
Author
Sandstrom, K.M.Koch, E.W.
Leroy, A.K.
Rosolowsky, E.
Emsellem, E.
Smith, R.J.
Egorov, O.V.
Williams, T.G.
Larson, K.L.
Lee, J.C.
Schinnerer, E.
Thilker, D.A.
Barnes, A.T.
Belfiore, F.
Bigiel, F.
Blanc, G.A.
Bolatto, A.D.
Boquien, M.
Cao, Y.
Chastenet, J.
Chevance, M.
Chiang, I.-D.
Dale, D.A.
Faesi, C.M.
Glover, S.C.O.
Grasha, K.

Groves, B.
Hassani, H.
Henshaw, J.D.
Hughes, A.
Kim, J.
Klessen, R.S.
Kreckel, K.
Kruijssen, J.M.D.
Lopez, L.A.
Liu, D.
Meidt, S.E.
Murphy, E.J.
Pan, H.-A.
Querejeta, M.
Saito, T.
Sardone, A.
Sormani, M.C.
Sutter, J.
Usero, A.
Watkins, E.J.
Affiliation
Steward Observatory, University of ArizonaIssue Date
2023-02-16
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American Astronomical SocietyCitation
Karin M. Sandstrom et al 2023 ApJL 944 L8Journal
Astrophysical Journal LettersRights
© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
JWST observations of polycyclic aromatic hydrocarbon (PAH) emission provide some of the deepest and highest resolution views of the cold interstellar medium (ISM) in nearby galaxies. If PAHs are well mixed with the atomic and molecular gas and illuminated by the average diffuse interstellar radiation field, PAH emission may provide an approximately linear, high-resolution, high-sensitivity tracer of diffuse gas surface density. We present a pilot study that explores using PAH emission in this way based on Mid-Infrared Instrument observations of IC 5332, NGC 628, NGC 1365, and NGC 7496 from the Physics at High Angular resolution in Nearby GalaxieS-JWST Treasury. Using scaling relationships calibrated in Leroy et al., scaled F1130W provides 10-40 pc resolution and 3σ sensitivity of Σgas ∼ 2 M ⊙ pc−2. We characterize the surface densities of structures seen at <7 M ⊙ pc−2 in our targets, where we expect the gas to be H i-dominated. We highlight the existence of filaments, interarm emission, and holes in the diffuse ISM at these low surface densities. Below ∼10 M ⊙ pc−2 for NGC 628, NGC 1365, and NGC 7496 the gas distribution shows a “Swiss cheese”-like topology due to holes and bubbles pervading the relatively smooth distribution of the diffuse ISM. Comparing to recent galaxy simulations, we observe similar topology for the low-surface-density gas, though with notable variations between simulations with different setups and resolution. Such a comparison of high-resolution, low-surface-density gas with simulations is not possible with existing atomic and molecular gas maps, highlighting the unique power of JWST maps of PAH emission. © 2023. The Author(s). Published by the American Astronomical Society.Note
Open access journalISSN
2041-8205Version
Final Published Versionae974a485f413a2113503eed53cd6c53
10.3847/2041-8213/aca972
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Except where otherwise noted, this item's license is described as © 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.