paper

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

arXiv:2212.09774 · doi:10.3847/2041-8213/acab01

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 ( kpc) spatially resolved measurements of CO (1-0) and CO (2-1) intensity, , and mid-IR intensity, , at 8, 12, 22, and 24m. The vs. relationship is reasonably described by a power law with slopes and normalization K km s at MJy sr. 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 , in good agreement with other work. The m and m bands, with strong PAH features, show steeper CO vs. mid-IR slopes than the m and 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 () and anti-correlates with SFR/. At 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.

arXiv comment29 pages, 13 figures, key quantitative results in Table 3, Accepted as part of a PHANGS-JWST Focus Issue to appear in ApJ

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