Quantification of the age dependence of mid-infrared star formation rate indicators

Calzetti, Daniela, Kennicutt, Robert C., Adamo, Angela, Sandstrom, Karin, Dale, Daniel A., Elmegreen, Bruce, Gallagher, John S., Gregg, Benjamin, Bajaj, Varun, Böker, Torsten, Bortolini, Giacomo, Boyer, Martha, Correnti, Matteo, De Looze, Ilse, Draine, Bruce T., Duarte-Cabral, Ana ORCID: https://orcid.org/0000-0002-5259-4774, Faustino Vieira, Helena, Grasha, Kathryn, Hunt, L. K., Johnson, Kelsey E., Klessen, Ralf S., Krumholz, Mark R., Lai, Thomas S.-Y., Lapeer, Drew, Linden, Sean T., Messa, Matteo, Östlin, Göran, Pedrini, Alex, Relaño, Mònica, Sabbi, Elena, Schinnerer, Eva, Skillman, Evan, Smith, Linda J., Tosi, Monica, Walter, Fabian and Weinbeck, Tony D. 2025. Quantification of the age dependence of mid-infrared star formation rate indicators. The Astrophysical Journal 991 (2) , 198. 10.3847/1538-4357/adfbe0

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Abstract

We combine James Webb Space Telescope images of the nearby galaxy NGC 5194 in the hydrogen recombination line Paα (1.8756 μm) from the Cycle 1 program JWST-FEAST with 21 μm dust continuum images from the Cycle 2 Treasury program JWGT to quantify the difference in the calibration of mid-infrared star formation rates (SFRs) between H II regions and galaxies. We use archival Hubble Space Telescope Hα imaging to correct the Paα emission for the effects of dust attenuation. Our data confirm previous results that the dust-corrected Paα flux is tightly correlated with the 21 μm emission at the scales of H II regions. When combined with published JWST data for the H II regions of the galaxy NGC 628 and Spitzer Space Telescope 24 μm data for whole galaxies and for kiloparsec-size galaxy regions, we show that the L(24)–L(Paα) relation has exponent > 1 across six decades in luminosity. In addition, the hybrid 24 μm + Hα SFR indicator has a scaling constant about 4.4 times higher for H II regions than for whole galaxies, also in agreement with previous results. Models of stellar populations with a range of star formation histories reveal that the observed trends can be entirely ascribed to and quantified with the contribution to the infrared emission by stellar populations older than ∼5–6 Myr. Based on the models’ results, we provide (1) a calibration for the infrared SFR across 6 orders of magnitude in L(24), from H II regions to luminous galaxies, and (2) a prescription for the scaling constant of the hybrid infrared SFR indicators as a function of the star formation timescale.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Type: cc-by
Publisher:	American Astronomical Society
ISSN:	0004-637X
Date of First Compliant Deposit:	7 October 2025
Date of Acceptance:	8 August 2025
Last Modified:	07 Oct 2025 11:15
URI:	https://orca.cardiff.ac.uk/id/eprint/181521

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