Detailed lens modeling and kinematics of the submillimeter galaxy G09v1.97

An analysis of CO, H₂O, H₂O⁺, and dust continuum emission

¹ Department of Space, Earth & Environment, Chalmers University of Technology SE-412 96 Gothenburg, Sweden
² Department of Physics, Institute for Computational Cosmology, Durham University South Road Durham DH 13LE, UK
³ School of Physics & Astronomy, University of Nottingham, University Park Nottingham NG7 2RD, UK
⁴ School of Mathematics, Statistics and Physics, Newcastle University Newcastle upon Tyne NE1 7RU, UK
⁵ School of Astronomy and Space Science, Nanjing University Nanjing 210093, China
⁶ Department of Physics & Astronomy, University of California Irvine Irvine CA 92697, USA
⁷ Sorbonne Université, UPMC Université Paris 6 and CNRS, UMR 7095, Institut d’Astrophysique de Paris 98bis Boulevard Arago 75014 Paris, France
⁸ Laboratoire d’Astrophysique de Marseille, Aix-Marseille Univ., CNRS, CNES Marseille, France
⁹ Instituto de Física y Astronomía, Universidad de Valparaíso Avda. Gran Bretaña 1111 Valparaíso, Chile
¹⁰ Astronomical Observatory Institute, Faculty of Physics, Adam Mickiewicz University ul. Słoneczna 36 60-286 Poznań, Poland
¹¹ Leiden Observatory, Leiden University PO Box 9513 2300 RA Leiden, The Netherlands
¹² National Radio Astronomy Observatory Charlottesville VA, USA
¹³ Millennium Nucleus for Galaxies (MINGAL) Santiago, Chile

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 11 July 2024
Accepted: 15 January 2026

Abstract

Context. While the formation mechanisms of intensely starbursting galaxies at high redshift remain unknown, one possible mechanism for producing these intense rates of star formation is via mergers and interactions. However, detecting these at high redshift remains a challenge. Observations of high-redshift gravitationally lensed galaxies provide a way to study the interstellar medium and environment of these extreme starbursts in detail.

Aims. We aim to use high angular resolution observations of dust continuum, CO(6−5), H₂O(2₁₁ − 2₀₂), and H₂O⁺(2₀₂ − 1₁₁) emission to constrain the ongoing processes in the z = 3.63 gravitationally lensed submillimeter galaxy H-ATLAS J083051.0+013224 (G09v1.97).

Methods. We used the sophisticated lens modeling software PYAUTOLENS to perform both parametric and nonparametric source modeling. We created a demagnified source plane CO(6−5) emission line cube and performed the kinematic modeling using ^3DBAROLO. Additionally, we investigated the properties of the continuum and molecular line emission in the source plane.

Results. We find that the regions of CO(6−5) and H₂O(2₁₁ − 2₀₂) emission are closely matched in the source plane, but that the dust continuum emission is more compact. We find that our lens modeling results do not require more than one source, contrary to what has been found in previous studies. Instead, we find that G09v1.97 resembles a rotating disk with V_max/σ¯ = 2.8 ± 0.4, along with evidence of residual emission indicative of noncircular motions such as outflows, tidal tails, or an additional background galaxy.

Conclusions. We suggest that the origin of the noncircular motions might be associated with a biconical outflow or a tidal tail from an interaction; alternatively, this might indicate the possible presence of an additional galaxy. We calculated the dynamical mass, gas mass, star formation rate, and depletion time for G09v1.97, along with a high star formation rate and low gas depletion time. In combination, this suggests that G09v1.97 has recently undergone an interaction, triggering intense star formation, while also being in the process of settling into a disk.