JWST Observations of Starbursts: Relations between PAH features and CO clouds in the starburst galaxy M 82

March 2025 • 2025A&A...695A.202V

Authors • Villanueva, V. • Bolatto, A. D. • Herrera-Camus, R. • Leroy, A. • Fisher, D. B. • Levy, R. C. • Böker, T. • Boogaard, L. • Cronin, S. A. • Dale, D. A. • Emig, K. • De Looze, I. • Donnelly, G. P. • Lai, T. S. -Y. • Lenkic, L. • Lopez, L. A. • Lopez, S. • Meier, D. S. • Ott, J. • Relano, M. • Smith, J. D. • Tarantino, E. • Veilleux, S. • Walter, F. • van der Werf, P.

Abstract • We present a study of new 7.7–11.3 μm data obtained with the James Webb Space Telescope Mid-InfraRed Instrument in the starburst galaxy M 82. In particular, we focus on the dependency of the integrated CO(1–0) line intensity on the MIRI-F770W and MIRI-F1130W filter intensities to investigate the correlation between H₂ content and the 7.7 and 11.3 μm features from polycyclic aromatic hydrocarbons (PAH) in M 82's outflows. To perform our analysis, we identify CO clouds using the archival ¹²CO(J = 1 ‑ 0) NOEMA moment 0 map within 2 kpc from the center of M 82, with sizes ranging between ∼21 and 270 pc; then, we compute the CO-to-PAH relations for the 306 validated CO clouds. On average, the power-law slopes for the two relations in M 82 are lower than what is seen in local main-sequence spirals. In addition, there is a moderate correlation between I_{CO(1 ‑ 0)} ‑ I_{7.7 μm}/I_{11.3 μm} for some of the CO cloud groups analyzed in this work. Our results suggest that the extreme conditions in M 82 translate into CO not tracing the full budget of molecular gas in smaller clouds, perhaps as a consequence of photoionization and/or emission suppression of CO molecules due to hard radiation fields from the central starburst.

Links

• PREPRINT http://arxiv.org/abs/2501.14893
• POSTSCRIPT https://www.aanda.org/10.1051/0004-6361/202553891/postscript
• ELECTR https://doi.org/10.1051%2F0004-6361%2F202553891
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2025A%26A...695A.202V
• PDF https://www.aanda.org/10.1051/0004-6361/202553891/pdf
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2025A%26A...695A.202V