The Galaxy Activity, Torus, and Outflow Survey (GATOS)

X. Molecular gas clumpiness under the influence of AGN

¹ Observatorio de Madrid, OAN-IGN, Alfonso XII, 3, E-28014 Madrid, Spain
² Centro de Astrobiología (CAB, CSIC-INTA), Camino Bajo del Castillo s/n, E-28692 Villanueva de la Cañada, Madrid, Spain
³ Observatoire de Paris, LUX, PSL University, Sorbonne Université, CNRS, F-75014 Paris, France
⁴ Collège de France, 11 Place Marcelin Berthelot, 75231 Paris, France
⁵ Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
⁶ Department of Physics & Astronomy, University of South Carolina, Columbia, SC 29208, USA
⁷ Kavli Institute for Particle Astrophysics & Cosmology (KIPAC), Stanford University, Stanford, CA 94305, USA
⁸ Instituto de Radioastronomía y Astrofísica (IRyA-UNAM), Antigua Carretera a Pátzcuaro #8701 Ex-Hda. San José de la Huerta, C.P., 58089 Morelia, Michoacán, Mexico
⁹ Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹⁰ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
¹¹ Department of Physics & Astronomy, University of Alaska Anchorage, Anchorage, AK 99508-4664, USA
¹² Department of Astronomy, University of Geneva, 1290 Versoix, Switzerland
¹³ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
¹⁴ Departamento de Física de la Tierra y Astrofísica, Fac. de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁵ Instituto de Física de Partículas y del Cosmos IPARCOS, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁶ Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, Pasadena, CA 91125, USA
¹⁷ Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX13RH, UK
¹⁸ School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
¹⁹ Institute of Astrophysics, Foundation for Research and Technology – Hellas (FORTH), Voutes 70013 Heraklion, Greece
²⁰ School of Sciences, European University Cyprus, Diogenes street, Engomi, 1516 Nicosia, Cyprus
²¹ School of Physics & Astronomy, University of Southampton, Southampton, SO17 1BJ Hampshire, UK
²² Telespazio UK for the European Space Agency (ESA), ESAC, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
²³ Space Telescope Science Institute, 3700 San Martin Drive Baltimore, MD 21218, USA
²⁴ Department of Physics and Astronomy, The University of Texas at San Antonio, 1 UTSA Circle, San Antonio, TX 78249, USA
²⁵ Instituto de Física Fundamental, CSIC, Calle Serrano 123, 28006 Madrid, Spain
²⁶ Centro de Astrobiología (CAB, CSIC/INTA), Ctra de Torrejón a Ajalvir, km 4, 28850 Torrejón de Ardoz, Madrid, Spain
²⁷ Departamento de Física, CCNE, Universidade Federal de Santa Maria, Av. Roraima 1000, 97105-900 Santa Maria, RS, Brazil

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Received: 18 July 2025
Accepted: 17 October 2025

Abstract

The distribution of molecular gas on small scales regulates star formation and the growth of supermassive black holes in galaxy centers. Yet, the role of active galactic nuclei (AGN) feedback in shaping this distribution remains poorly constrained. We investigate how AGNs influence the small-scale structure of molecular gas in galaxy centers by measuring the clumpiness of CO(3 − 2) emission observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in the nuclear regions (50 − 200 pc from the AGNs) of 16 nearby Seyfert galaxies from the Galaxy Activity, Torus, and Outflow Survey (GATOS). To quantify clumpiness we applied three different methods: (1) the median of the pixel-by-pixel contrast between the original and smoothed maps; (2) the ratio of the total excess flux to the total flux, after subtracting the background smoothed emission; and (3) the fraction of total flux coming from clumpy regions, interpreted as the mass fraction in clumps. We find a negative correlation between molecular gas clumpiness and AGN X-ray luminosity (L_X), suggesting that higher AGN activity is associated with smoother gas distributions. All methods reveal a turnover in this relation around L_X = 10⁴² erg s⁻¹, possibly indicating a threshold above which AGN feedback becomes efficient at dispersing dense molecular structures and suppressing future star formation. Our findings provide new observational evidence that AGN feedback can smooth out dense gas structures in galaxy centers.