Molecular gas stratification and disturbed kinematics in the Seyfert galaxy MCG-05-23-16 revealed by JWST and ALMA

¹ Instituto de Astrofísica de Canarias, Calle Vía Láctea, s/n, E-38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
³ Instituto de Física Fundamental, CSIC, Calle Serrano 123, 28006 Madrid, Spain
⁴ Centro de Astrobiología (CAB), CSIC-INTA, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁵ Observatorio Astronómico Nacional (OAN-IGN)-Observatorio de Madrid, Alfonso XII, 3, 28014 Madrid, Spain
⁶ Max Planck Institute for Extraterrestrial Physics (MPE), Giessenbachstr.1, 85748 Garching, Germany
⁷ LERMA, Observatoire de Paris, Collège de France, PSL University, 837 CNRS, Sorbonne University, Paris, France
⁸ Department of Physics and Astronomy, The University of Texas at San Antonio, 1 UTSA Circle, San Antonio, Texas 78249, USA
⁹ School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
¹⁰ Departmento de Física de la Tierra y Astrofísica, Fac. de CC Físicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
¹¹ Instituto de Física de Partículas y del Cosmos IPARCOS, Fac. CC Físicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
¹² Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
¹³ Institute of Astrophysics, Foundation for Research and Technology Hellas (FORTH), Heraklion 70013, Greece
¹⁴ School of Sciences, European University Cyprus, Diogenes street, Engomi, 1516 Nicosia, Cyprus
¹⁵ Instituto de Radioastronomía and Astrofísica (IRyA-UNAM), 3-72 (Xangari), 8701 Morelia, Mexico
¹⁶ Department of Physics & Astronomy, University of Alaska Anchorage, Anchorage, Alaska, USA
¹⁷ Department of Physics, University of Alaska, Fairbanks, Alaska 99775-5920, USA
¹⁸ Telespazio UK for the European Space Agency (ESA), ESAC, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Spain
¹⁹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²⁰ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
²¹ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
²² School of Physics & Astronomy, University of Southampton, High- 843 field, Southampton SO17 1BJ, UK
²³ Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
²⁴ Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281-S9, Gent B-9000, Belgium
²⁵ Department of Astronomy, School of Science, Graduate University for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588, Japan
²⁶ Kavli Institute for Particle Astrophysics & Cosmology (KIPAC), Stanford University, Stanford, CA 94305, USA
²⁷ Department of Physics & Astronomy, University of South Carolina, Columbia, SC 29208, USA
²⁸ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon, France
²⁹ Centre for Extragalactic Astronomy, Durham University, South Road, Durham DH1 3LE, UK

^⋆ Corresponding author; dcaesparza@gmail.com

Received: 4 October 2024
Accepted: 17 November 2024

Abstract

Understanding the processes that drive the morphology and kinematics of molecular gas in galaxies is crucial for comprehending star formation and, ultimately, galaxy evolution. Using data from the Galactic Activity, Torus and Outflow Survey (GATOS) obtained with the James Webb Space Telescope (JWST) and the archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), we study the behavior of the warm molecular gas at temperatures of hundreds of Kelvin and the cold molecular gas at tens of Kelvin in the galaxy MCG−05−23−16, which hosts an active galactic nucleus (AGN). Hubble Space Telescope (HST) images of this spheroidal galaxy, classified in the optical as S0, show a dust lane resembling a nuclear spiral and a surrounding ring. These features are also detected in CO(2−1) and H₂, and their morphologies and kinematics are consistent with rotation plus local inward gas motions along the kinematic minor axis in the presence of a nuclear bar. The H₂ transitions 0-0 S(3), 0-0 S(4), and 0-0 S(5), which trace warmer and more excited gas, show more disrupted kinematics than 0-0 S(1) and 0-0 S(2), including clumps of high velocity dispersion (of up to ∼160 km s⁻¹), in regions devoid of CO(2−1). The kinematics of one of these clumps, located ∼350 pc westward of the nucleus, are consistent with outflowing gas, possibly driven by localized star formation traced by polycyclic aromatic hydrocarbon emission at 11.3 μm. Overall, we observe a stratification of the molecular gas, with the colder gas located in the nuclear spiral, ring, and connecting arms, and most of the warmer gas with a higher velocity dispersion filling the inter-arm space. The compact jet, approximately 200 pc in size, detected with Very Large Array (VLA) observations, does not appear to significantly affect the distribution and kinematics of the molecular gas, possibly due to its limited intersection with the molecular gas disk.