MICONIC: Dual active galactic nuclei, star formation, and ionised gas outflows in NGC 6240 seen with MIRI/JWST

Context. Galaxy mergers are an important and complex phase during the evolution of galaxies. They may trigger nuclear activity and/or strong star forming episodes in galaxy centres that potentially alter the evolution of the system. Aims. As part of the guaranteed time observations program Mid-Infrared Characterization Of Nearby Iconic galaxy Centers (MICONIC), we used the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument on board the James Webb Space Telescope (JWST) to study NGC 6240. We aim to characterise the dual active galactic nuclei (AGN), the ionised gas outflows, and the main properties of the interstellar medium over a mapped area of 6.6″ × 7.7″. Aims. We obtained integral field spectroscopic mid-infrared data (wavelength from 4.9 to 28 μm) of NGC 6240. We modelled the emission lines through a kinematic decomposition that accounts for the possible existence of various components. Methods. We have resolved both nuclei of NGC 6240 for the first time in the full 5−28 μm spectral range. The fine structure lines in the southern (S) nucleus are broader than for the northern (N) nucleus (full width at half maximum of ≥1500 versus ∼700 km s −1 on average, respectively). High excitation lines, such as [Ne V], [Ne VI], and [Mg V], are clearly detected in the N nucleus. In the S nucleus, the same lines can be detected but only after a decomposition of the polycyclic aromatic hydrocarbon features in the integrated spectrum, due to a combination of a strong mid-IR continuum, broad emission lines, and intense star formation (SF). The SF is distributed all over the mapped field of view of 3.5 kpc × 4.1 kpc (projected), with the maximum located around the S nucleus. Both nuclear regions appear to be connected by a bridge region that is detected with all the emission lines. Based on the observed MRS line ratios and the high velocity dispersion ( σ ∼ 600 km s −1 ), shocks also dominate the emission in this system. We detected the presence of outflows as a bubble north-west from the N nucleus and at the S nucleus. We estimated an ionised mass outflow rate of 1.4 ± 0.3 M ⊙ yr −1 and 1.8 ± 0.2 M ⊙ yr −1 , respectively. Given the derived kinetic power of these outflows, both the AGN and the starburst could have triggered them.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2024-12-23
DOI
https://doi.org/10.1051/0004-6361/202452437
Citations
13
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
4.31

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article

MICONIC: Dual active galactic nuclei, star formation, and ionised gas outflows in NGC 6240 seen with MIRI/JWST

D. Dicken, A. Alonso-Herrero, Fabian Walter, Bernhard R. Brandl et al.
13 citations
Astronomy and Astrophysics
Galaxies: Formation, Evolution, Phenomena
4.31
article

MICONIC: Dual active galactic nuclei, star formation, and ionised gas outflows in NGC 6240 seen with MIRI/JWST

D. Dicken, A. Alonso-Herrero, Fabian Walter, Bernhard R. Brandl, I. García-Bernete, Laura Hermosa Muñoz, Alvaro Labiano, Victorine A. Buiten, L. Colina, M. Baes, P. Guillard, Göran Östlin, M. J. Ward, L. Pantoni, T. P. Ray, Fergus R. Donnan, Gillian Wright, Th. Henning, M. Güdel, Torsten Böker, Pierre-Olivier Lagage, P. van der Werf
article en
13 citations

Abstract

Context. Galaxy mergers are an important and complex phase during the evolution of galaxies. They may trigger nuclear activity and/or strong star forming episodes in galaxy centres that potentially alter the evolution of the system. Aims. As part of the guaranteed time observations program Mid-Infrared Characterization Of Nearby Iconic galaxy Centers (MICONIC), we used the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument on board the James Webb Space Telescope (JWST) to study NGC 6240. We aim to characterise the dual active galactic nuclei (AGN), the ionised gas outflows, and the main properties of the interstellar medium over a mapped area of 6.6″ × 7.7″. Aims. We obtained integral field spectroscopic mid-infrared data (wavelength from 4.9 to 28 μm) of NGC 6240. We modelled the emission lines through a kinematic decomposition that accounts for the possible existence of various components. Methods. We have resolved both nuclei of NGC 6240 for the first time in the full 5−28 μm spectral range. The fine structure lines in the southern (S) nucleus are broader than for the northern (N) nucleus (full width at half maximum of ≥1500 versus ∼700 km s −1 on average, respectively). High excitation lines, such as [Ne V], [Ne VI], and [Mg V], are clearly detected in the N nucleus. In the S nucleus, the same lines can be detected but only after a decomposition of the polycyclic aromatic hydrocarbon features in the integrated spectrum, due to a combination of a strong mid-IR continuum, broad emission lines, and intense star formation (SF). The SF is distributed all over the mapped field of view of 3.5 kpc × 4.1 kpc (projected), with the maximum located around the S nucleus. Both nuclear regions appear to be connected by a bridge region that is detected with all the emission lines. Based on the observed MRS line ratios and the high velocity dispersion ( σ ∼ 600 km s −1 ), shocks also dominate the emission in this system. We detected the presence of outflows as a bubble north-west from the N nucleus and at the S nucleus. We estimated an ionised mass outflow rate of 1.4 ± 0.3 M ⊙ yr −1 and 1.8 ± 0.2 M ⊙ yr −1 , respectively. Given the derived kinetic power of these outflows, both the AGN and the starburst could have triggered them.

Astronomy and AstrophysicsVol. 693
Leiden University (NL), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), University of Vienna (AT), Dublin Institute For Advanced Studies (IE), Stockholm University (SE), Institut Universitaire de France (FR), Durham University (GB), Université Paris Cité (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), Institut d'Astrophysique de Paris (FR), European Space Agency (FR), Ghent University (BE), ETH Zurich (CH), Sorbonne Université (FR), University of Oxford (GB), Astrophysique, Instrumentation et Modélisation (FR), European Space Astronomy Centre (ES), Royal Observatory (GB), Max Planck Institute for Astronomy (DE), CEA Paris-Saclay (FR), Centro de Astrobiología (ES), Ministère de l'Enseignement Supérieur, de la Recherche et de l'Espace (FR), AlbaNova (SE), UK Astronomy Technology Centre (GB), Delft University of Technology (NL)
National Aeronautics and Space Administration, California Institute of Technology, Comunidad de Madrid, Space Telescope Science Institute, Swedish National Space Agency, Belgian Federal Science Policy Office, Centre National d’Etudes Spatiales, Ministerio de Ciencia e Innovación, Jet Propulsion Laboratory, European Regional Development Fund, Agencia Estatal de Investigación
Openalex Percentile: Top 6%
Galaxies: Formation, Evolution, Phenomena
4.31
DOIOpen Access PDFOpenAlex
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