The GASKAP-H I Survey Toward the Magellanic Clouds: Cold Atomic Gas Survival and Evolution in the Large Magellanic Cloud
Year: 2026
Type: article
Abstract: We use atomic hydrogen (H I ) absorption detections from the GASKAP-H I survey to investigate the properties of cold atomic gas in the Large Magellanic Cloud (LMC). Using the radiative transfer method, we decompose 155 sightlines into 330 cold neutral medium (CNM), 2 thermally unstable neutral medium (UNM), and 310 warm neutral medium (WNM) components. We find that the CNM in the LMC exhibits higher optical depths (median 0.46), lower spin temperatures (median ∼37 K), broader linewidths (median ∼4.9 km s −1 ), and slightly lower CNM fractions (median ∼23%) than in the Milky Way. We examine the connection between the CNM, molecular gas, and star formation, finding that CNM correlates more closely with molecular gas than WNM, while molecular gas shows a tighter relation with star formation. Molecular hydrogen (H 2 ) formation begins near N HI,CNM ∼ 10 20 cm −2 , and nearly all sightlines with N HI,CNM > 10 21 cm −2 contain molecular gas. The CNM fraction increases with visual extinction ( A V ), and the LMC maintains CNM fractions comparable to those in the Milky Way at substantially lower A V , likely due to higher local densities and a longer line-of-sight depth. Sightlines near expanding shells tend to show higher CNM fractions, although this is partly driven by higher total H I column densities. Finally, the CNM kinematics generally follow the H I disk rotation, with about 7% of components showing velocity offsets greater than 25 km s −1 , likely tracing inflows or outflows driven by stellar feedback or large-scale interactions within the Magellanic system.
Source: The Astrophysical Journal
Authors: Hongxing Chen, Snežana Stanimirović, James Dempsey, Jacco Th. van Loon, Yik Ki Ma, Hiep Nguyen, Nickolas M. Pingel, John M. Dickey, Min-Young Lee, N. M. McClure-Griffiths, Claire E. Murray, Lister Staveley-Smith, Denis Leahy, Callum Lynn, Antoine Marchal, Daniel R. Rybarczyk, Helga Dénes, Steven Gibson, Katherine Jameson, Ian Kemp, Ioana A. Stelea
Institutions: University of Wisconsin–Madison, Australian National University, Keele University, Max Planck Institute for Radio Astronomy, Indiana University, University of Tasmania, Korea Astronomy and Space Science Institute, SKA Observatory, Space Telescope Science Institute, Johns Hopkins University, The University of Western Australia, Université Paris Sciences et Lettres, Universidad San Francisco de Quito, Western Kentucky University, California Institute of Technology, Curtin University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7204115980