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Leroy, AK, Sandstrom, K, Rosolowsky, E, Belfiore, F, Bolatto, AD, Cao, Y, Koch, EW, Schinnerer, E, Barnes, AT, Bešlić, I, Bigiel, F, Blanc, GA, Chastenet, J, Chen, NM, Chevance, M, Chown, R, Congiu, E, Dale, DA, Egorov, OV, Emsellem, E , Eibensteiner, C, Faesi, CM, Glover, SCO, Grasha, K, Groves, B, Hassani, H, Henshaw, JD, Hughes, A, Jiménez-Donaire, MJ, Kim, J, Klessen, RS, Kreckel, K, Kruijssen, JMD, Larson, KL, Lee, JC, Levy, RC, Liu, D, Lopez, LA, Meidt, SE, Murphy, EJ, Neumann, J, Pessa, I, Pety, J, Saito, T, Sardone, A, Sun, J, Thilker, DA, Usero, A, Watkins, EJ, Whitcomb, CM and Williams, TG (2023) PHANGS-JWST First Results: Mid-infrared Emission Traces Both Gas Column Density and Heating at 100 pc Scales. Astrophysical Journal Letters, 944 (2). ISSN 2041-8205
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PHANGS-JWST First Results Mid-infrared Emission Traces Both Gas Column Density and Heating at 100 pc Scales.pdf - Published Version Available under License Creative Commons Attribution. Download (8MB) | Preview |
Abstract
We compare mid-infrared (mid-IR), extinction-corrected Hα, and CO (2-1) emission at 70-160 pc resolution in the first four PHANGS-JWST targets. We report correlation strengths, intensity ratios, and power-law fits relating emission in JWST’s F770W, F1000W, F1130W, and F2100W bands to CO and Hα. At these scales, CO and Hα each correlate strongly with mid-IR emission, and these correlations are each stronger than the one relating CO to Hα emission. This reflects that mid-IR emission simultaneously acts as a dust column density tracer, leading to a good match with the molecular-gas-tracing CO, and as a heating tracer, leading to a good match with the Hα. By combining mid-IR, CO, and Hα at scales where the overall correlation between cold gas and star formation begins to break down, we are able to separate these two effects. We model the mid-IR above I ν = 0.5 MJy sr−1 at F770W, a cut designed to select regions where the molecular gas dominates the interstellar medium (ISM) mass. This bright emission can be described to first order by a model that combines a CO-tracing component and an Hα-tracing component. The best-fitting models imply that ∼50% of the mid-IR flux arises from molecular gas heated by the diffuse interstellar radiation field, with the remaining ∼50% associated with bright, dusty star-forming regions. We discuss differences between the F770W, F1000W, and F1130W bands and the continuum-dominated F2100W band and suggest next steps for using the mid-IR as an ISM tracer.
| Item Type: | Article |
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| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences; Astronomy & Astrophysics |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 26 Sep 2024 16:06 |
| Last Modified: | 26 Sep 2024 16:15 |
| DOI or ID number: | 10.3847/2041-8213/acaf85 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/24284 |
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