The Detection of a Massive Chain of Dark H i Clouds in the GAMA G23 Field

Józsa, G. I.G.; Jarrett, T. H.; Cluver, M. E.; Wong, O. I.; Havenga, O.; Yao, H. F.M.; Marchetti, L.; Taylor, E. N.; Kamphuis, P.; MacCagni, F. M.; Ramaila, A. J.T.; Serra, P.; Smirnov, O. M.; White, S. V.; Kilborn, V.; Holwerda, B. W.; Hopkins, A. M.; Brough, S.; Pimbblet, K. A.; Driver, S. P.; Kuijken, K.

Abstract

We report on the detection of a large, extended H i cloud complex in the Galaxy and Mass Survey G23 field, located at a redshift of z ∼0.03, observed as part of the MeerKAT Habitat of Galaxies Survey campaign (a pilot survey to explore the mosaicing capabilities of the MeerKAT telescope). The cloud complex, with a total mass of 1010.0 M, lies in proximity to a large galaxy group with M dyn ∼1013.5 M. We identify seven H peak concentrations, interconnected as a tenuous chain structure, extending ∼400 kpc from east to west, with the largest (central) concentration containing 109.7 M in H gas distributed across 50 kpc. The main source is not detected in ultraviolet, optical, or infrared imaging. The implied gas mass-to-light ratio (M H I/L r) is extreme (>1000) even in comparison to other dark clouds. The complex has very little kinematic structure (110 km s-1), making it difficult to identify cloud rotation. Assuming pressure support, the total mass of the central concentration is > 1010.2 M, while a lower limit to the dynamical mass in the case of full rotational support is 1010.4 M. If the central concentration is a stable structure, it has to contain some amount of unseen matter, but potentially less than is observed for a typical galaxy. It is, however, not clear whether the structure has any gravitationally stable concentrations. We report a faint UV-optical-infrared source in proximity to one of the smaller concentrations in the gas complex, leading to a possible stellar association. The system nature and origins is enigmatic, potentially being the result of an interaction with or within the galaxy group it appears to be associated with.

Citation

Józsa, G. I., Jarrett, T. H., Cluver, M. E., Wong, O. I., Havenga, O., Yao, H. F., …Kuijken, K. (2022). The Detection of a Massive Chain of Dark H i Clouds in the GAMA G23 Field. The Astrophysical journal, 926(2), Article 167. https://doi.org/10.3847/1538-4357/ac402b

• Journal Article Type: Article
• Acceptance Date: Dec 6, 2021
• Online Publication Date: Feb 22, 2022
• Publication Date: Feb 20, 2022
• Deposit Date: Jan 11, 2022
• Publicly Available Date: Feb 23, 2022
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 926
• Issue: 2
• Article Number: 167
• DOI: https://doi.org/10.3847/1538-4357/ac402b
• Keywords: Intergalactic medium; Intergalactic clouds; Interstellar medium; Galaxies; Galaxy groups
• Public URL: https://hull-repository.worktribe.com/output/3910099