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Timescales of polycyclic aromatic hydrocarbon and dust continuum emission from gas clouds compared to molecular gas cloud lifetimes in PHANGS-JWST galaxies

Recent JWST mid-infrared (mid-IR) images, tracing polycyclic aromatic hydrocarbons (PAHs) and dust continuum emission, provide detailed views of the interstellar medium (ISM) in nearby galaxies. Leveraging PHANGS-JWST Cycle 1 and PHANGS-MUSE data, we measure the PAH and dust continuum emission lifet...

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Main Authors: Kim, Jaeyeon (Author) , Chevance, Mélanie (Author) , Ramambason, Lise (Author) , Kreckel, Kathryn (Author) , Klessen, Ralf S. (Author) , Dale, Daniel A. (Author) , Leroy, Adam K. (Author) , Sandstrom, Karin (Author) , Chown, Ryan (Author) , Williams, Thomas G. (Author) , Sarbadhicary, Sumit K. (Author) , Belfiore, Francesco (Author) , Bigiel, Frank (Author) , Congiu, Enrico (Author) , Egorov, Oleg (Author) , Emsellem, Eric (Author) , Glover, Simon (Author) , Grasha, Kathryn (Author) , Hughes, Annie (Author) , Kruijssen, J. M. Diederik (Author) , Lee, Janice C. (Author) , Pathak, Debosmita (Author) , Pessa, Ismael (Author) , Rosolowsky, Erik (Author) , Sun, Jiayi (Author) , Sutter, Jessica (Author) , Thilker, David A. (Author)
Format: Article (Journal)
Language:English
Published: 2025 August 1
In: The astrophysical journal
Year: 2025, Volume: 988, Issue: 2, Pages: 1-37
ISSN:1538-4357
DOI:10.3847/1538-4357/ade443
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.3847/1538-4357/ade443
Verlag, kostenfrei, Volltext: https://iopscience.iop.org/article/10.3847/1538-4357/ade443
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Author Notes:Jaeyeon Kim, Mélanie Chevance, Lise Ramambason, Kathryn Kreckel, Ralf S. Klessen, Daniel A. Dale, Adam K. Leroy, Karin Sandstrom, Ryan Chown, Thomas G. Williams, Sumit K. Sarbadhicary, Francesco Belfiore, Frank Bigiel, Enrico Congiu, Oleg V. Egorov, Eric Emsellem, Simon C.O. Glover, Kathryn Grasha, Annie Hughes, J.M. Diederik Kruijssen, Janice C. Lee, Debosmita Pathak, Ismael Pessa, Erik Rosolowsky, Jiayi Sun, Jessica Sutter, and David A. Thilker
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Summary:Recent JWST mid-infrared (mid-IR) images, tracing polycyclic aromatic hydrocarbons (PAHs) and dust continuum emission, provide detailed views of the interstellar medium (ISM) in nearby galaxies. Leveraging PHANGS-JWST Cycle 1 and PHANGS-MUSE data, we measure the PAH and dust continuum emission lifetimes of gas clouds across 17 nearby star-forming galaxies by analyzing the relative spatial distributions of mid-IR (7.7-11.3 μm) and Hα emission at various scales. We find that the mid-IR emitting timescale of gas clouds in galactic disks (excluding centers) ranges from 10-30 Myr. After star formation is detected in Hα, mid-IR emission persists for 3-7 Myr during the stellar feedback phase, covering 70%-80% of the Hα emission. This significant overlap is due to intense radiation from star-forming regions, illuminating the surrounding PAHs and dust grains. In most galaxies, the mid-IR time-scale closely matches the molecular cloud lifetime measured with CO. Although mid-IR emission is complex, as influenced by ISM distribution, radiation, and abundances of dust and PAHs, the similarity between the two timescales suggests that once gas clouds form with compact mid-IR emission, they quickly provide sufficient shielding for stable CO formation. This is likely due to our focus on molecular gas-rich regions of galaxies with near-solar metallicity. Finally, we find that the mid-IR emitting timescale is longer in galaxies with well-defined H ii regions and less structured backgrounds, allowing photons to more efficiently heat the ambient ISM surrounding the H ii regions, rather than contributing to diffuse emission. This suggests that the shape of the ISM also influences mid-IR emission.
Item Description:Online verfügbar: 25. Juli 2025
Gesehen am 17.12.2025
Physical Description:Online Resource
ISSN:1538-4357
DOI:10.3847/1538-4357/ade443

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