Polycyclic Aromatic Hydrocarbon and CO(2–1) Emission at 50–150 pc Scales in 70 Nearby Galaxies

Abstract Combining Atacama Large Millimeter/submillimeter Array CO(2–1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2–1) and polycyclic aromatic hydrocarbon (PAH) emission at ≈100 pc resolution in 70 nearby star-forming galaxies. Leveraging a new Cycle 2 JWST Treasury program targeting nearby galaxies, we expand the sample size by more than an order of magnitude compared to previous ≈100 pc resolution CO–PAH comparisons. In regions of galaxies where most of the gas is likely to be molecular, we find strong correlations between CO(2–1) and 3.3 μ m, 7.7 μ m, and 11.3 μ m PAH emission, estimated from JWST’s F335M, F770W, and F1130W filters. We derive power-law relations between CO(2–1) and PAH emission, with indices in the range 0.8–1.3, implying relatively weak variations in the observed CO-to-PAH ratios across our sample. We find that CO-to-PAH ratios and scaling relationships near H ii regions are similar to those in diffuse sight lines. The main difference between the two types of regions is that sight lines near H ii regions show higher intensities in all tracers. Galaxy centers show higher overall intensities and enhanced CO-to-PAH ratios compared to galaxy disks. Individual galaxies show 0.19 dex scatter in the normalization of CO at fixed I PAH , and this normalization anticorrelates with specific star formation rate and correlates with stellar mass. We provide a prescription that accounts for galaxy-to-galaxy variations, representing our best current empirical predictor to estimate CO(2–1) intensity from PAH emission, allowing one to take advantage of JWST’s excellent sensitivity and resolution to trace cold gas.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-04-07
DOI
https://doi.org/10.3847/1538-4357/adbd40
Citations
13
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
15.01

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article

Polycyclic Aromatic Hydrocarbon and CO(2–1) Emission at 50–150 pc Scales in 70 Nearby Galaxies

Karin M. Sandstrom, David A. Thilker, Dario Colombo, E. J. Murphy et al.
13 citations
The Astrophysical Journal
Astrophysics and Star Formation Studies
15.01
article

Polycyclic Aromatic Hydrocarbon and CO(2–1) Emission at 50–150 pc Scales in 70 Nearby Galaxies

Karin M. Sandstrom, David A. Thilker, Dario Colombo, E. J. Murphy, M. Boquien, Debosmita Pathak, Yu-Hsuan Teng, Sharon E. Meidt, Jaeyeon Kim, Francesco Belfiore, Eve C. Ostriker, Mélanie Chevance, Ryan Chown, Erik Rosolowsky, Éric Emsellem, Hamid Hassani, Lukas Neumann, Gagandeep S. Anand, Jakob S. den Brok, Elias K. Oakes, Hao He, Ashley T. Barnes, Frank Bigiel, Thomas G. Williams, Jérémy Chastenet, Sumit K. Sarbadhicary, Tony D. Weinbeck, Kirsten L. Larson, Jonathan D. Henshaw, Eva Schinnerer, Elizabeth J. Watkins, Jiayi Sun, Dalya Baron, Cosima Eibensteiner, Ralf S. Klessen, Alberto D. Bolatto, Jessica Sutter, Adam K. Leroy, Eric W. Koch, Kathryn Kreckel, Hsi-An Pan, Daniel A. Dale, Oleg V. Egorov, Zein Bazzi, Hannah Koziol, Yixian Cao, Janice Lee
article en
13 citations

Abstract

Abstract Combining Atacama Large Millimeter/submillimeter Array CO(2–1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2–1) and polycyclic aromatic hydrocarbon (PAH) emission at ≈100 pc resolution in 70 nearby star-forming galaxies. Leveraging a new Cycle 2 JWST Treasury program targeting nearby galaxies, we expand the sample size by more than an order of magnitude compared to previous ≈100 pc resolution CO–PAH comparisons. In regions of galaxies where most of the gas is likely to be molecular, we find strong correlations between CO(2–1) and 3.3 μ m, 7.7 μ m, and 11.3 μ m PAH emission, estimated from JWST’s F335M, F770W, and F1130W filters. We derive power-law relations between CO(2–1) and PAH emission, with indices in the range 0.8–1.3, implying relatively weak variations in the observed CO-to-PAH ratios across our sample. We find that CO-to-PAH ratios and scaling relationships near H ii regions are similar to those in diffuse sight lines. The main difference between the two types of regions is that sight lines near H ii regions show higher intensities in all tracers. Galaxy centers show higher overall intensities and enhanced CO-to-PAH ratios compared to galaxy disks. Individual galaxies show 0.19 dex scatter in the normalization of CO at fixed I PAH , and this normalization anticorrelates with specific star formation rate and correlates with stellar mass. We provide a prescription that accounts for galaxy-to-galaxy variations, representing our best current empirical predictor to estimate CO(2–1) intensity from PAH emission, allowing one to take advantage of JWST’s excellent sensitivity and resolution to trace cold gas.

The Astrophysical JournalVol. 983(1)
Université Claude Bernard Lyon 1 (FR), Tamkang University (TW), École Normale Supérieure de Lyon (FR), University of Wyoming (US), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), European Southern Observatory (DE), University of Bonn (DE), Harvard University (US), Whitman College (US), University of Connecticut (US), Johns Hopkins University (US), University of Alberta (CA), Carnegie Institution for Science (US), Princeton University (US), Heidelberg University (DE), National Radio Astronomy Observatory (US), Arcetri Astrophysical Observatory (IT), University of Manchester (GB), Ghent University (BE), University of California San Diego (US), Institute for Advanced Study (US), University of Oxford (GB), Centre de Recherche Astrophysique de Lyon (FR), Max Planck Institute for Extraterrestrial Physics (DE), Kavli Institute for Particle Astrophysics and Cosmology (US), Czech Society for Oriental Studies (CZ), Max Planck Institute for Astronomy (DE), Joint Space Science Institute (US), Université Bourgogne Franche-Comté (FR), Center for Astrophysics Harvard & Smithsonian (US), Carnegie Observatories (US), Observatoire de la Côte d’Azur (FR), Columbus Community Clinical Oncology Program (US), The Ohio State University (US), Liverpool John Moores University (GB), University of Maryland, College Park (US)
National Aeronautics and Space Administration, Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Agencia Nacional de Investigación y Desarrollo
Openalex Percentile: Top 1%
Astrophysics and Star Formation Studies
15.01
DOIOpen Access PDFOpenAlex
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