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arXiv · 2507.18355

Molecular gas in a system of two interacting galaxies overlapping on the line-of-sight

Anaëlle Halle·Barbara Mazzilli Ciraulo·Daniel Maschmann·Anne-Laure Melchior·Françoise Combes
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Abstract

Galaxy interactions can disturb gas in galactic discs, compress it, excite it, and enhance star formation. An intriguing system likely consisting of two interacting galaxies overlapping on the line-of-sight was previously studied through ionised gas observations from the integral-field spectrograph Mapping Nearby Galaxies at APO (MaNGA). A decomposition into two components using MaNGA spectra, together with a multi-wavelength study, allowed to characterise the system as a minor-merger with interaction-induced star-formation, and maybe AGN activity. We use new interferometric observations of the CO(1-0) gas of this system from the NOrthern Extended Millimeter Array (NOEMA) to confront and combine the spatially-resolved ionised and molecular gas observations. Mock NOEMA and MaNGA data are computed from simulated systems of two discs and compared to the observations. The NOEMA observations of the molecular gas, dynamically colder than the ionised gas, help to precise the configuration of the system, which we revisit as being a major merger. Combination of ionised and molecular gas data allow us to study the star-formation efficiency of the system.

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Anaëlle Halle, Barbara Mazzilli Ciraulo, Daniel Maschmann, Anne-Laure Melchior, Françoise Combes. 2025-07-24. Molecular gas in a system of two interacting galaxies overlapping on the line-of-sight. https://doi.org/10.1051/0004-6361%2F202556579

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