The MALATANG survey: Star formation, dense gas, and active galactic nucleus feedback in NGC 1068

¹ Department of Astronomy, Xiamen University, Zengcuo’an West Road Xiamen 361005
² School of Astronomy and Space Science, Nanjing University, Nanjing 210093
³ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093
⁴ Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua road Nanjing 210023
⁵ School of Physical Science and Technology, Guangxi University, Nanning 530004
⁶ Research Center for Astronomical Computing, Zhejiang Laboratory, Hangzhou 311121
⁷ Shandong Key Laboratory of Space Environment and Exploration Technology, College of Physics and Electronic Information, Dezhou University, Dezhou 253023
⁸ Department of Physics, Hebei Normal University (Physics Postdoctoral Research Station at Hebei Normal University), Shijiazhuang 050024
⁹ Guo Shoujing Institute for Astronomy, Hebei Normal University, Shijiazhuang 050024
¹⁰ Hebei Advanced Thin Films Laboratory, Shijiazhuang 050024
¹¹ Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astro-Math Building, AS/NTU, No.1, Sec. 4, Roosevelt Rd Taipei 10617
¹² Department of Astronomy, Yonsei University 50 Yonsei-ro Seodaemun-gu Seoul 03722, Republic of Korea
¹³ Institute of Astronomy, Graduate School of Science, The University of Tokyo 2-21-1 Osawa Mitaka Tokyo 181-0015, Japan
¹⁴ Joetsu University of Education, Yamayashiki-machi Joetsu Niigata 943-8512, Japan
¹⁵ Cosmic Dawn Center (DAWN) Copenhagen, Denmark
¹⁶ DTU-Space, Technical University of Denmark Elektrovej 327 DK-2800 Kgs. Lyngby, Denmark
¹⁷ Department of Physics and Astronomy, University College London Gower Street London WC1E 6BT, UK

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Received: 21 October 2025
Accepted: 26 November 2025

Abstract

Aims. We investigated the interplay between dense molecular gas, star formation, and active galactic nucleus (AGN) feedback in the luminous IR galaxy NGC 1068 at sub-kiloparsec scales.

Methods. We present the HCN (4-3) and HCO⁺ (4-3) maps of NGC 1068 obtained with JCMT as part of the Mapping the dense molecular gas in the strongest star-forming galaxies (MALATANG) project, and perform spatially resolved analyses of their correlations with IR luminosity and soft X-ray emission.

Results. The spatially resolved relations between the luminosities of IR dust emission and dense molecular gas tracers (L_IR − L′_dense) are found to be nearly linear, without clear evidence of excess contributions from AGN activity. The spatially resolved X-ray emission (L^gas_{0.5−2 KeV}) displays a radially dependent twofold correlation with the star formation rate (SFR), suggesting distinct gas-heating mechanisms are at play in areas between the galaxy center and the outer regions. A super-linear scaling is obtained in galactic center regions with SFR surface densities (Σ_SFR) > 8.2 × 10⁻⁶ M_⊙ yr⁻¹ kpc⁻²: log(L^gas_{0.5−2 KeV}/erg s⁻¹) = 2.2 log(SFR/M_⊙ yr⁻¹) + 39.1. We further find a statistically significant super-linear correlation (β = 1.34 ± 0.86) between L^gas_{0.5−2 KeV}/SFR and the HCN(4–3)/CO(1–0) intensity ratio, whereas no such trend is seen for HCO⁺(4-3)/CO(1-0) or CO(3-2)/CO(1-0). These findings indicate that AGN feedback does not dominate star formation regulation on sub-kiloparsec scales, and that the excitation of dense gas traced by HCN (4-3) may be more directly influenced by high-energy feedback processes compared to HCO⁺ (4-3) and CO (3-2).