NGC 2992: Interplay between the multiphase disc, wind, and radio bubbles

¹ SISSA, Via Bonomea 265, 34136 Trieste, Italy
e-mail: mazanch@sissa.it
² INAF – Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
³ IFPU – Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
⁴ INAF – Istituto di Radioastronomia, Italian ARC, Via Piero Gobetti 101, 40129 Bologna, Italy
⁵ INFN, Sezione di Trieste, Via Valerio 2, Trieste 34127, Italy
⁶ Dipartimento di Fisica, Università di Trieste, Sezione di Astronomia, Via G. B. Tiepolo 11, 34131 Trieste, Italy
⁷ Department of Physics, University of Milan Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
⁸ INAF – Osservatorio Astronomico di Roma, Via di Frascati 33, 00040 Monteporzio Catone, Rome, Italy
⁹ INAF – OAS Bologna, Via Gobetti 101, 40129 Bologna, Italy
¹⁰ ASI – Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
¹¹ Dept. of Physics, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Rome, Italy
¹² Dept. of Astronomy, University of Maryland, College Park, MD 20742, USA
¹³ NASA – Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
¹⁴ INFN – Roma Tor Vergata, Via Della Ricerca Scientifica 1, 00133 Rome, Italy
¹⁵ Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze, Italy
¹⁶ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50127 Firenze, Italy

Received: 19 December 2022
Accepted: 6 August 2023

Abstract

We present an analysis of the gas kinematics in NGC 2992 based on VLT/MUSE, ALMA, and VLA data. Our aim is to characterise the disc, the wind, and their interplay in the cold molecular and warm ionised phases. NGC 2992 is a changing-look Seyfert known to host both a nuclear ultrafast outflow (UFO), and an AGN-driven kiloparsec-scale ionised wind. CO(2−1) and Hα arise from a multiphase disc with an inclination of 80 deg and radii of 1.5 and 1.8 kpc, respectively. By modelling the gas kinematics, we find that the velocity dispersion of the cold molecular phase, σ_gas, is consistent with that of star forming galaxies at the same redshift, except in the inner 600 pc region, and in the region between the cone walls and the disc, where σ_gas is a factor of 3−4 larger than in star forming galaxies for both the cold molecular and the warm ionised phases. This suggests that a disc–wind interaction locally boosts the gas turbulence. We detect a clumpy ionised wind in Hβ, [O III], Hα, and [N II] distributed in two wide-opening-angle ionisation cones reaching scales of 7 kpc (40 arcsec). The [O III] wind expands with a velocity exceeding −1000 km s⁻¹ in the inner 600 pc, which is a factor of approximately five greater than the previously reported wind velocity. Based on spatially resolved electron density and ionisation parameter maps, we infer an ionised outflow mass of M_of, ion = (3.2 ± 0.3)×10⁷ M_⊙, and a total ionised outflow rate of Ṁ_of,ion = 13.5 ± 1 M_⊙ yr⁻¹. We detected ten clumps of cold molecular gas located above and below the disc in the ionisation cones, reaching maximum projected distances of 1.7 kpc and showing projected bulk velocities of up to 200 km s⁻¹. On these scales, the wind is multiphase, with a fast ionised component and a slower molecular one, and a total mass of M_{of, ion + mol} = 5.8 × 10⁷ M_⊙, of which the molecular component carries the bulk of the mass, namely M_of, mol = 4.3 × 10⁷ M_⊙. The dusty molecular outflowing clumps and the turbulent ionised gas are located at the edges of the radio bubbles, suggesting that the bubbles interact with the surrounding medium through shocks, as also supported by the [O I]/Hα ratio. Conversely, both the large opening angle and the dynamical timescale of the ionised wind detected in the ionisation cones on 7 kpc scales indicate that this is not related to the radio bubbles but instead likely associated with a previous AGN episode. Finally, we detect a dust reservoir that is co-spatial with the molecular disc, with a cold dust mass of M_dust = (4.04 ± 0.03)×10⁶ M_⊙, which is likely responsible for the extended Fe Kα emission seen on 200 pc scales in hard X-rays and interpreted as reflection by cold dust.