Magnetized H <scp>i</scp> superbubbles in the Small Magellanic Cloud revealed by the POSSUM pilot survey

ABSTRACT Neutral hydrogen (H i) bubbles and shells are common in the interstellar medium (ISM). Studying their properties provides insight into the characteristics of the local ISM as well as the galaxy in which the bubbles reside. We report the detection of magnetic fields associated with superbubbles in the nearby irregular galaxy, the Small Magellanic Cloud (SMC). Using the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM) pilot survey, we obtain a high-density grid ($\approx 25 \, \rm sources\, deg^{-2}$) of Faraday rotation measure (RM) from polarized sources behind the SMC. This provides a sufficiently large number of RM measurements to study the magnetic properties of three of the largest H i shells previously identified in the SMC. The RM profiles as a function of distance from the shell centre show characteristic patterns at angular scales comparable to the shell size. We demonstrate that this can be explained by magnetohydrodynamic simulation models of bubbles expanding in magnetized environments. From the observations, we estimate the line-of-sight magnetic field strength at the edges of the shells is enhanced by $\sim 1\, \rm \mu G$ with respect to their centres. This is an order of magnitude larger than the field strength in the ambient medium ($\sim 0.1\, \rm \mu G$) estimated based on the expansion velocity of the shells. This paper highlights the power of densely mapped RM grids in studying the magnetic properties of galactic substructures beyond the Milky Way.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-09-27
DOI
https://doi.org/10.1093/mnras/stae2245
Citations
1
Primary Topic
Solar and Space Plasma Dynamics
Type
article
Field-Weighted Citation Impact
0.33

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article

Magnetized H i superbubbles in the Small Magellanic Cloud revealed by the POSSUM pilot survey

Yik Ki, N. M. McClure‐Griffiths, Cameron L. Van Eck, Takuya Akahori et al.
1 citations
Monthly Notices of the Royal Astronomical Society
Solar and Space Plasma Dynamics
0.33
article

Magnetized H i superbubbles in the Small Magellanic Cloud revealed by the POSSUM pilot survey

Yik Ki, N. M. McClure‐Griffiths, Cameron L. Van Eck, Takuya Akahori, Christoph Federrath, G. Heald, J. Price, B. M. Gaensler, J. D. Livingston, C. S. Anderson, S. P. O’Sullivan, Jennifer West, D. A. Leahy, Amit Seta, Mehrnoosh Tahani, S Lyla Jung
article en
1 citations

Abstract

ABSTRACT Neutral hydrogen (H i) bubbles and shells are common in the interstellar medium (ISM). Studying their properties provides insight into the characteristics of the local ISM as well as the galaxy in which the bubbles reside. We report the detection of magnetic fields associated with superbubbles in the nearby irregular galaxy, the Small Magellanic Cloud (SMC). Using the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM) pilot survey, we obtain a high-density grid ($\approx 25 \, \rm sources\, deg^{-2}$) of Faraday rotation measure (RM) from polarized sources behind the SMC. This provides a sufficiently large number of RM measurements to study the magnetic properties of three of the largest H i shells previously identified in the SMC. The RM profiles as a function of distance from the shell centre show characteristic patterns at angular scales comparable to the shell size. We demonstrate that this can be explained by magnetohydrodynamic simulation models of bubbles expanding in magnetized environments. From the observations, we estimate the line-of-sight magnetic field strength at the edges of the shells is enhanced by $\sim 1\, \rm \mu G$ with respect to their centres. This is an order of magnitude larger than the field strength in the ambient medium ($\sim 0.1\, \rm \mu G$) estimated based on the expansion velocity of the shells. This paper highlights the power of densely mapped RM grids in studying the magnetic properties of galactic substructures beyond the Milky Way.

Monthly Notices of the Royal Astronomical SocietyVol. 534(3)
Australian National University (AU), Universidad Complutense de Madrid (ES), Herzberg Institute of Astrophysics (CA), Commonwealth Scientific and Industrial Research Organisation (AU), Australia Telescope National Facility (AU), Australian Research Council (AU), University of Calgary (CA), University of California, Santa Cruz (US), University of Toronto (CA), University of Oxford (GB), ASTRO-3D (AU), Kavli Institute for Particle Astrophysics and Cosmology (US), Max Planck Institute for Radio Astronomy (DE), National Astronomical Observatory of Japan (JP)
Stanford University, Science and Industry Endowment Fund, National Computational Infrastructure, Comunidad de Madrid, UK Research and Innovation, Australian Government, Canada Foundation for Innovation, European Commission, Commonwealth Scientific and Industrial Research Organisation, Canada Research Chairs, Government of Western Australia, Gauss Centre for Supercomputing, Natural Sciences and Engineering Research Council of Canada, European Research Council, Australian Research Council, Leibniz-Gemeinschaft
Openalex Percentile: Top 34%
Solar and Space Plasma Dynamics
0.33
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