Ammonia in the interstellar medium of a starbursting disc at z = 2.6

Doherty, M. J.; Geach, J. E.; Ivison, R. J.; Menten, K. M.; Jacob, A. M.; Forbrich, J.; Dye, S.

Abstract

We report the detection of the ground state rotational emission of ammonia, ortho-NH3 (JK = 10 → 00) in a gravitationally lensed intrinsically hyperluminous star-bursting galaxy at z = 2.6. The integrated line profile is consistent with other molecular and atomic emission lines which have resolved kinematics well modelled by a 5 kpc-diameter rotating disc. This implies that the gas responsible for NH3 emission is broadly tracing the global molecular reservoir, but likely distributed in pockets of high density (n ≳ 5 × 104 cm−3). With a luminosity of 2.8 × 106 L☉, the NH3 emission represents 2.5 × 10−7 of the total infrared luminosity of the galaxy, comparable to the ratio observed in the Kleinmann-Low nebula in Orion and consistent with sites of massive star formation in the Milky Way. If LNH3/LIR serves as a proxy for the 'mode' of star formation, this hints that the nature of star formation in extreme starbursts in the early Universe is similar to that of Galactic star-forming regions, with a large fraction of the cold interstellar medium in this state, plausibly driven by a storm of violent disc instabilities in the gas-dominated disc. This supports the 'full of Orions' picture of star formation in the most extreme galaxies seen close to the peak epoch of stellar mass assembly.

Citation

Doherty, M. J., Geach, J. E., Ivison, R. J., Menten, K. M., Jacob, A. M., Forbrich, J., & Dye, S. (2022). Ammonia in the interstellar medium of a starbursting disc at z = 2.6. Monthly Notices of the Royal Astronomical Society: Letters, 517(1), L60-L64. https://doi.org/10.1093/mnrasl/slac111

• Journal Article Type: Article
• Acceptance Date: Sep 15, 2022
• Online Publication Date: Sep 23, 2022
• Publication Date: Jan 1, 2022
• Deposit Date: Oct 5, 2022
• Publicly Available Date: Oct 14, 2022
• Journal: Monthly Notices of the Royal Astronomical Society: Letters
• Electronic ISSN: 1745-3933
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 517
• Issue: 1
• Pages: L60-L64
• DOI: https://doi.org/10.1093/mnrasl/slac111
• Keywords: Space and Planetary Science, Astronomy and Astrophysics
• Public URL: https://nottingham-repository.worktribe.com/output/11756183
• Publisher URL: https://academic.oup.com/mnrasl/article-abstract/517/1/L60/6712731?redirectedFrom=fulltext
• Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2022 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.