학술논문
PHANGS-JWST First Results: A Global and Moderately Resolved View of Mid-Infrared and CO Line Emission from Galaxies at the Start of the JWST Era
Document Type
Working Paper
Author
Leroy, Adam K.; Bolatto, Alberto D.; Sandstrom, Karin; Rosolowsky, Erik; Barnes, Ashley. T.; Bigiel, F.; Boquien, Médéric; Brok, Jakob S. den; Cao, Yixian; Chastenet, Jérémy; Chevance, Mélanie; Chiang, I-Da; Chown, Ryan; Colombo, Dario; Ellison, Sara L.; Emsellem, Eric; Grasha, Kathryn; Henshaw, Jonathan D.; Hughes, Annie; Klessen, Ralf S.; Koch, Eric W.; Kim, Jaeyeon; Kreckel, Kathryn; Kruijssen, J. M. Diederik; Larson, Kirsten L.; Lee, Janice C.; Levy, Rebecca C.; Lin, Lihwai; Liu, Daizhong; Meidt, Sharon E.; Pety, Jérôme; Querejeta, Miguel; Rubio, Mónica.; Saito, Toshiki; Salim, Samir; Schinnerer, Eva; Sormani, Mattia C.; Sun, Jiayi; Thilker, David A.; Usero, Antonio; Watkins, Stuart N. Vogel Elizabeth J.; Whitcomb, Cory M.; Williams, Thomas G.; Wilson, Christine D.
Source
Subject
Language
Abstract
We explore the relationship between mid-infrared (mid-IR) and CO rotational line emission from massive star-forming galaxies, which is one of the tightest scalings in the local universe. We assemble a large set of unresolved and moderately ($\sim 1$ kpc) spatially resolved measurements of CO (1-0) and CO (2-1) intensity, $I_{\rm CO}$, and mid-IR intensity, $I_{\rm MIR}$, at 8, 12, 22, and 24$\mu$m. The $I_{\rm CO}$ vs. $I_{\rm MIR}$ relationship is reasonably described by a power law with slopes $0.7{-}1.2$ and normalization $I_{\rm CO} \sim 1$ K km s$^{-1}$ at $I_{\rm MIR} \sim 1$ MJy sr$^{-1}$. Both the slopes and intercepts vary systematically with choice of line and band. The comparison between the relations measured for CO~(1-0) and CO (2-1) allow us to infer that $R_{21} \propto I_{\rm MIR}^{0.2}$, in good agreement with other work. The $8\mu$m and $12\mu$m bands, with strong PAH features, show steeper CO vs. mid-IR slopes than the $22\mu$m and $24\mu$m, consistent with PAH emission arising not just from CO-bright gas but also from atomic or CO-dark gas. The CO-to-mid-IR ratio correlates with global galaxy stellar mass ($M_\star$) and anti-correlates with SFR/$M_\star$. At $\sim 1$ kpc resolution, the first four PHANGS-JWST targets show CO to mid-IR relationships that are quantitatively similar to our larger literature sample, including showing the steep CO-to-mid-IR slopes for the JWST PAH-tracing bands, although we caution that these initial data have a small sample size and span a limited range of intensities.
Comment: 29 pages, 13 figures, key quantitative results in Table 3, Accepted as part of a PHANGS-JWST Focus Issue to appear in ApJ
Comment: 29 pages, 13 figures, key quantitative results in Table 3, Accepted as part of a PHANGS-JWST Focus Issue to appear in ApJ