PHANGS-JWST First Results: Mid-infrared Emission Traces Both Gas Column Density and Heating at 100 pc Scales - INSU - Institut national des sciences de l'Univers
Journal Articles The Astrophysical journal letters Year : 2023

PHANGS-JWST First Results: Mid-infrared Emission Traces Both Gas Column Density and Heating at 100 pc Scales

Adam K. Leroy
  • Function : Author
Karin Sandstrom
  • Function : Author
Erik Rosolowsky
  • Function : Author
Francesco Belfiore
  • Function : Author
Alberto D. Bolatto
  • Function : Author
Yixian Cao
  • Function : Author
Eric W. Koch
  • Function : Author
Eva Schinnerer
  • Function : Author
Ashley. T. Barnes
  • Function : Author
Ivana Bešlić
  • Function : Author
F. Bigiel
  • Function : Author
Guillermo A. Blanc
  • Function : Author
Jérémy Chastenet
  • Function : Author
Ness Mayker Chen
  • Function : Author
Mélanie Chevance
  • Function : Author
Ryan Chown
  • Function : Author
Enrico Congiu
  • Function : Author
Daniel A. Dale
  • Function : Author
Oleg V. Egorov
  • Function : Author
Cosima Eibensteiner
  • Function : Author
Christopher M. Faesi
  • Function : Author
Simon C. O. Glover
  • Function : Author
Kathryn Grasha
  • Function : Author
Brent Groves
  • Function : Author
Hamid Hassani
  • Function : Author
Jonathan D. Henshaw
  • Function : Author
María J. Jiménez-Donaire
  • Function : Author
Jaeyeon Kim
  • Function : Author
Ralf S. Klessen
  • Function : Author
Kathryn Kreckel
  • Function : Author
J. M. Diederik Kruijssen
  • Function : Author
Kirsten L. Larson
  • Function : Author
Janice C. Lee
  • Function : Author
Rebecca C. Levy
  • Function : Author
Daizhong Liu
  • Function : Author
Laura A. Lopez
  • Function : Author
Sharon E. Meidt
  • Function : Author
Eric J. Murphy
  • Function : Author
Justus Neumann
  • Function : Author
Ismael Pessa
  • Function : Author
Toshiki Saito
  • Function : Author
Amy Sardone
  • Function : Author
Jiayi Sun
  • Function : Author
David A. Thilker
  • Function : Author
Antonio Usero
  • Function : Author
Elizabeth J. Watkins
  • Function : Author
Cory M. Whitcomb
  • Function : Author
Thomas G. Williams
  • Function : Author

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.
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insu-04473227 , version 1 (22-02-2024)

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Adam K. Leroy, Karin Sandstrom, Erik Rosolowsky, Francesco Belfiore, Alberto D. Bolatto, et al.. PHANGS-JWST First Results: Mid-infrared Emission Traces Both Gas Column Density and Heating at 100 pc Scales. The Astrophysical journal letters, 2023, 944, ⟨10.3847/2041-8213/acaf85⟩. ⟨insu-04473227⟩
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