A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling

A. Nestor Shachar; A. Sternberg; R. Genzel; D. Liu; S. H. Price; C. Pulsoni; L. J. Tacconi; R. Herrera-Camus; N. M. Förster Schreiber; A. Burkert; J. B. Jolly; D. Lutz; S. Wuyts; C. Barfety; Y. Cao; J. Chen; R. Davies; F. Eisenhauer; J. M. Espejo Salcedo; L. L. Lee; M. Lee; T. Naab; S. Pastras; T. T. Shimizu; E. Sturm; G. Tozzi; H. Übler

doi:10.3847/1538-4357/ade2d0

A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling

A. Nestor Shachar, A. Sternberg, R. Genzel, D. Liu, S. H. Price, C. Pulsoni, L. J. Tacconi, R. Herrera-Camus, N. M. Förster Schreiber, A. Burkert, J. B. Jolly, D. Lutz, S. Wuyts, C. Barfety, Y. Cao, J. Chen, R. Davies, F. Eisenhauer, J. M. Espejo Salcedo, L. L. LeeM. Lee, T. Naab, S. Pastras, T. T. Shimizu, E. Sturm, G. Tozzi, H. Übler

Research output: Contribution to journal › Article › peer-review

Abstract

A unique galaxy at z = 2.2, zC406690, has a striking clumpy large-scale ring structure that persists from rest-frame UV to near-infrared, yet has an ordered rotation and lies on the star formation main sequence. We combine new JWST/NIRCam and Atacama Large Millimeter/submillimeter Array (ALMA) band 4 observations, together with previous Very Large Telescope/SINFONI integral field spectroscopy and Hubble Space Telescope imaging to reexamine its nature. The high-resolution Hα kinematics is best fitted if the mass is distributed within a ring with total mass M_ring ≈ 2 × 10¹⁰ M_⊙ and radius R_ring = 4.6 kpc, together with a central undetected mass component (e.g., a “bulge”) with a dynamical mass of M_bulge = 8 × 10¹⁰ M_⊙. We also consider a purely flux-emitting ring superposed over a faint exponential disk, or a highly “cuspy” dark matter halo, both disfavored against a massive ring model. The low-resolution CO(4-3) line and 142 GHz continuum emission imply total molecular and dust gas masses of M_mol,gas = 7.1 × 10¹⁰ M_⊙ and M_dust = 3 × 10⁸ M_⊙, respectively, over the entire galaxy, giving a dust-to-gas ratio of 0.7%. We estimate that roughly half the gas and dust mass lie inside the ring, and that ∼10% of the total dust is in a foreground screen that attenuates the stellar light of the bulge in the rest-frame UV to near-infrared. Sensitive high-resolution ALMA observations will be essential to confirm this scenario and study the gas and dust distribution.

Original language	English
Article number	182
Journal	Astrophysical Journal
Volume	988
Issue number	2
Early online date	23 Jul 2025
DOIs	https://doi.org/10.3847/1538-4357/ade2d0
Publication status	Published - 31 Aug 2025

Acknowledgements

This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. The JWST data used in this paper are associated with program #1727 and can be found in MAST at doi:10.17909/x7ct-ef43. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2013.1.00668.S and ADS/JAO.ALMA#2017.1.01020.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.

Funding

This work was supported by the German Science Foundation via DFG/DIP grant STE/1869-2 GE 625/17-1. A.N.S. and A.S. are supported by the Center for Computational Astrophysics (CCA) of the Flatiron Institute, and the Mathematics and Science Division of the Simons Foundation, USA. H.Ü. acknowledges funding by the European Union (ERC APEX, 101164796). T.N. acknowledges the support of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC-2094—390783311 of the DFG Cluster of Excellence “ORIGINS.” N.M.F.S., C.B., J.C., J.M.E.S., and G.T. acknowledge funding by the European Union (ERC Advanced grant GALPHYS, 101055023). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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Nestor Shachar, A., Sternberg, A., Genzel, R., Liu, D., Price, S. H., Pulsoni, C., Tacconi, L. J., Herrera-Camus, R., Förster Schreiber, N. M., Burkert, A., Jolly, J. B., Lutz, D., Wuyts, S., Barfety, C., Cao, Y., Chen, J., Davies, R., Eisenhauer, F., Espejo Salcedo, J. M., ... Übler, H. (2025). A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling. Astrophysical Journal, 988(2), Article 182. https://doi.org/10.3847/1538-4357/ade2d0

Nestor Shachar, A, Sternberg, A, Genzel, R, Liu, D, Price, SH, Pulsoni, C, Tacconi, LJ, Herrera-Camus, R, Förster Schreiber, NM, Burkert, A, Jolly, JB, Lutz, D, Wuyts, S, Barfety, C, Cao, Y, Chen, J, Davies, R, Eisenhauer, F, Espejo Salcedo, JM, Lee, LL, Lee, M, Naab, T, Pastras, S, Shimizu, TT, Sturm, E, Tozzi, G & Übler, H 2025, 'A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling', Astrophysical Journal, vol. 988, no. 2, 182. https://doi.org/10.3847/1538-4357/ade2d0

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title = "A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling",

abstract = "A unique galaxy at z = 2.2, zC406690, has a striking clumpy large-scale ring structure that persists from rest-frame UV to near-infrared, yet has an ordered rotation and lies on the star formation main sequence. We combine new JWST/NIRCam and Atacama Large Millimeter/submillimeter Array (ALMA) band 4 observations, together with previous Very Large Telescope/SINFONI integral field spectroscopy and Hubble Space Telescope imaging to reexamine its nature. The high-resolution Hα kinematics is best fitted if the mass is distributed within a ring with total mass Mring ≈ 2 × 1010 M⊙ and radius Rring = 4.6 kpc, together with a central undetected mass component (e.g., a “bulge”) with a dynamical mass of Mbulge = 8 × 1010 M⊙. We also consider a purely flux-emitting ring superposed over a faint exponential disk, or a highly “cuspy” dark matter halo, both disfavored against a massive ring model. The low-resolution CO(4-3) line and 142 GHz continuum emission imply total molecular and dust gas masses of Mmol,gas = 7.1 × 1010 M⊙ and Mdust = 3 × 108 M⊙, respectively, over the entire galaxy, giving a dust-to-gas ratio of 0.7\%. We estimate that roughly half the gas and dust mass lie inside the ring, and that ∼10\% of the total dust is in a foreground screen that attenuates the stellar light of the bulge in the rest-frame UV to near-infrared. Sensitive high-resolution ALMA observations will be essential to confirm this scenario and study the gas and dust distribution.",

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T1 - A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam

T2 - Kinematic Observations and Analytical Modelling

AU - Nestor Shachar, A.

AU - Sternberg, A.

AU - Genzel, R.

AU - Liu, D.

AU - Price, S. H.

AU - Pulsoni, C.

AU - Tacconi, L. J.

AU - Herrera-Camus, R.

AU - Förster Schreiber, N. M.

AU - Burkert, A.

AU - Jolly, J. B.

AU - Lutz, D.

AU - Wuyts, S.

AU - Barfety, C.

AU - Cao, Y.

AU - Chen, J.

AU - Davies, R.

AU - Eisenhauer, F.

AU - Espejo Salcedo, J. M.

AU - Lee, L. L.

AU - Lee, M.

AU - Naab, T.

AU - Pastras, S.

AU - Shimizu, T. T.

AU - Sturm, E.

AU - Tozzi, G.

AU - Übler, H.

PY - 2025/8/31

Y1 - 2025/8/31

N2 - A unique galaxy at z = 2.2, zC406690, has a striking clumpy large-scale ring structure that persists from rest-frame UV to near-infrared, yet has an ordered rotation and lies on the star formation main sequence. We combine new JWST/NIRCam and Atacama Large Millimeter/submillimeter Array (ALMA) band 4 observations, together with previous Very Large Telescope/SINFONI integral field spectroscopy and Hubble Space Telescope imaging to reexamine its nature. The high-resolution Hα kinematics is best fitted if the mass is distributed within a ring with total mass Mring ≈ 2 × 1010 M⊙ and radius Rring = 4.6 kpc, together with a central undetected mass component (e.g., a “bulge”) with a dynamical mass of Mbulge = 8 × 1010 M⊙. We also consider a purely flux-emitting ring superposed over a faint exponential disk, or a highly “cuspy” dark matter halo, both disfavored against a massive ring model. The low-resolution CO(4-3) line and 142 GHz continuum emission imply total molecular and dust gas masses of Mmol,gas = 7.1 × 1010 M⊙ and Mdust = 3 × 108 M⊙, respectively, over the entire galaxy, giving a dust-to-gas ratio of 0.7%. We estimate that roughly half the gas and dust mass lie inside the ring, and that ∼10% of the total dust is in a foreground screen that attenuates the stellar light of the bulge in the rest-frame UV to near-infrared. Sensitive high-resolution ALMA observations will be essential to confirm this scenario and study the gas and dust distribution.

AB - A unique galaxy at z = 2.2, zC406690, has a striking clumpy large-scale ring structure that persists from rest-frame UV to near-infrared, yet has an ordered rotation and lies on the star formation main sequence. We combine new JWST/NIRCam and Atacama Large Millimeter/submillimeter Array (ALMA) band 4 observations, together with previous Very Large Telescope/SINFONI integral field spectroscopy and Hubble Space Telescope imaging to reexamine its nature. The high-resolution Hα kinematics is best fitted if the mass is distributed within a ring with total mass Mring ≈ 2 × 1010 M⊙ and radius Rring = 4.6 kpc, together with a central undetected mass component (e.g., a “bulge”) with a dynamical mass of Mbulge = 8 × 1010 M⊙. We also consider a purely flux-emitting ring superposed over a faint exponential disk, or a highly “cuspy” dark matter halo, both disfavored against a massive ring model. The low-resolution CO(4-3) line and 142 GHz continuum emission imply total molecular and dust gas masses of Mmol,gas = 7.1 × 1010 M⊙ and Mdust = 3 × 108 M⊙, respectively, over the entire galaxy, giving a dust-to-gas ratio of 0.7%. We estimate that roughly half the gas and dust mass lie inside the ring, and that ∼10% of the total dust is in a foreground screen that attenuates the stellar light of the bulge in the rest-frame UV to near-infrared. Sensitive high-resolution ALMA observations will be essential to confirm this scenario and study the gas and dust distribution.

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ER -

A Large-scale Ring Galaxy at z = 2.2 Revealed by JWST/NIRCam: Kinematic Observations and Analytical Modelling

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Acknowledgements

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