Clumpy, dense gas in the outflow of NGC 1266

Otter, Justin Atsushi, Alatalo, Katherine, Rowlands, Kate, Patil, Pallavi, Skarbinski, Maya, Dysarz, Lauren, Lacy, Mark, Jiménez-Donaire, María J., Aalto, Susanne, Davis, Timothy A. ORCID: https://orcid.org/0000-0003-4932-9379, Fodor, Antoniu, French, K. Decker, Harada, Nanase, Heckman, Timothy, Kishikawa, Ryo, Lopez, Sebastian, Luo, Yuanze, Martin, Sergio, Medling, Anne M., Nyland, Kristina, Petric, Andreea, Roy, Namrata, Sato, Mamiko, Sazonova, Elizaveta, Smercina, Adam and Tripathi, Akshat 2026. Clumpy, dense gas in the outflow of NGC 1266. The Astrophysical Journal 997 (2) , 361. 10.3847/1538-4357/ae2c5a

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Abstract

Outflows are one of the most spectacular mechanisms through which active galactic nuclei (AGN) impact their host galaxy, though the role of AGN-driven outflows in global star formation regulation across the galaxy population is unclear. NGC 1266 is an excellent case study for investigating outflows and star formation quenching because it is a nearby (D ∼ 30 Mpc) AGN host galaxy with an outflow driving shocks through the interstellar medium (ISM) and has recently quenched its star formation outside the nucleus. While previous works have studied the molecular outflow from its CO emission, to fully characterize the impact the outflow has on the ISM observations probing the dense, cold gas are necessary. Our Atacama Large Millimeter/submillimeter Array Cycle 0 observations do not detect a molecular outflow in 13CO(2–1) and yield a lower limit of 12CO/13CO ≥ 250, suggesting a highly optically thin CO outflow with low 13CO abundance. In contrast, we detect substantial HCN(1–0) emission in the outflow, with an HCN(1–0)/12CO(1–0) ratio of 0.09, consistent with global measurements of many star-forming galaxies and luminous infrared galaxies. We conclude that the CO emission traces a diffuse component of the molecular gas with a low optical depth, whereas the HCN(1–0) traces dense clumps of gas entrained in the outflow. We measure an upper limit molecular outflow rate of <85 M⊙ yr–1. Assuming the ongoing nuclear star formation and outflow continue at the same rates, NGC 1266 will deplete its gas reservoir in 450 Myr or longer, indicating that relatively low-level AGN feedback is capable of gradually expelling the molecular gas reservoir after a rapid quenching event.

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:	5 February 2026
Date of Acceptance:	10 December 2025
Last Modified:	05 Feb 2026 10:15
URI:	https://orca.cardiff.ac.uk/id/eprint/184441

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