The Diffuse Ionized Gas Halo of the Large Magellanic Cloud

B. M. Smart; L. M. Haffner; K. A. Barger; D. A. Ciampa; A. S. Hill; D. Krishnarao; G. J. Madsen

doi:10.3847/1538-4357/acc06e

The Astrophysical Journal (Jan 2023)

The Diffuse Ionized Gas Halo of the Large Magellanic Cloud

B. M. Smart,
L. M. Haffner,
K. A. Barger,
D. A. Ciampa,
A. S. Hill,
D. Krishnarao,
G. J. Madsen

Affiliations

B. M. Smart: ORCiD; Department of Astronomy, University of Washington , Seattle, WA 98195, USA ; [email protected]; Department of Physics, Astronomy, and Mathematics, University of Hertfordshire , Hatfield AL10 9AB, UK; Department of Astronomy, University of Wisconsin-Madison , Madison, WI 53706, USA
L. M. Haffner: ORCiD; Department of Astronomy, University of Wisconsin-Madison , Madison, WI 53706, USA; Department of Physical Sciences, Embry-Riddle Aeronautical University , Daytona Beach, FL 32114-3900, USA
K. A. Barger: ORCiD; Department of Physics & Astronomy, Texas Christian University , Fort Worth, TX 76129, USA
D. A. Ciampa: ORCiD; Department of Physics & Astronomy, Texas Christian University , Fort Worth, TX 76129, USA
A. S. Hill: ORCiD; Department of Computer Science, Math, Physics, and Statistics, University of British Columbia , Okanagan Campus, Kelowna, BC V1V 1V7, Canada; Space Science Institute , Boulder, CO 80301, USA; Dominion Radio Astrophysical Observatory , Herzberg Program in Astronomy and Astrophysics, National Research Council Canada, Penticton, BC, Canada
D. Krishnarao: ORCiD; Department of Astronomy, University of Wisconsin-Madison , Madison, WI 53706, USA; NSF Astronomy and Astrophysics Postdoctoral Fellow, Johns Hopkins University , Baltimore, MD, 21218, USA; Department of Physics, Colorado College , Colorado Springs, CO, USA; Space Telescope Science Institute , Baltimore, MD 21218, USA
G. J. Madsen: Institute of Astronomy, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UK

DOI: https://doi.org/10.3847/1538-4357/acc06e
Journal volume & issue: Vol. 948, no. 2
p. 118

Abstract

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The Large Magellanic Cloud (LMC) has an extensive H α emission halo that traces an extended, warm ionized component of its interstellar medium. Using the Wisconsin H α Mapper telescope, we present the first kinematic H α survey of an extensive region around the LMC, from ( ℓ , b ) = (264.°5, − 45.°5) to (295.°5, − 19.°5), covering +150 ≤ v _LSR ≤ + 390 km s ^−1 . We find that ionized hydrogen exists throughout the galaxy and extends several degrees beyond detected neutral hydrogen emission $(\mathrm{log}\left({N}_{{\rm{H}}\,{\rm\small{I}}/{\mathrm{cm}}^{-2}}\right)\approx 18.3)$ as traced by 21 cm in current surveys. Using the column density structure of the neutral gas and stellar line-of-sight depths as a guide, we estimate the upper limit mass of the ionized component of the LMC to be roughly M _ionized ≈ (0.6–1.8) × 10 ^9 M _☉ , which is comparable to the total neutral atomic gas mass in the same region ( M _neutral ≈ 0.76–0.85 × 10 ^9 M _☉ ). Considering only the atomic phases, we find M _ionized / M _ionized+neutral , to be 46%–68% throughout the LMC and its extended halo. Additionally, we find an ionized gas cloud that extends off of the LMC at ( ℓ , b ) ≈ (285°, − 28°) into a region previously identified as the Leading Arm complex. This gas is moving at a similar line-of-sight velocity as the LMC and has M _ionized / M _ionized+neutral = 13%–51%. This study, combined with previous studies of the SMC and extended structures of the Magellanic Clouds, continues to suggest that warm, ionized gas is as massive and dynamically important as the neutral gas in the Magellanic System.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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