Letter to the Editor

Supernova remnants on the outskirts of the Large Magellanic Cloud

¹ Dr. Karl Remeis Observatory, Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
² School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
³ Australian SKA Regional Centre, Curtin Institute of Radio Astronomy, Curtin University, GPO Box U1987 Perth, WA 6845, Australia
⁴ The Inter-University Institute for Data Intensive Astronomy (IDIA), Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
⁵ CSIRO, Space and Astronomy, PO Box 1130 Bentley, WA 6102, Australia
⁶ Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
⁷ Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
⁸ Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, PO Box 94 Makhanda 6140, South Africa
⁹ South African Radio Astronomy Observatory, 2 Fir Street, Black River Park, Observatory 7295, South Africa
¹⁰ Department of Physics, Maynooth University, Maynooth, Co Kildare, Ireland
¹¹ CSIRO, Space and Astronomy, Australia Telescope National Facility, PO Box 76 Epping, NSW 1710, Australia
¹² Dominion Radio Astrophysical Observatory, Herzberg Astronomy and Astrophysics Research Centre, National Research Council Canada, PO Box 248 Penticton, BC V2A 6J9, Canada
¹³ Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
¹⁴ Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, 11 rue de l’Université, 67000 Strasbourg, France
¹⁵ Cerro Tololo Inter-American Observatory, NOIRLab, Cassilla 603, La Serena, Chile
¹⁶ Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan

^⋆ Corresponding author; manami.sasaki@fau.de

Received: 9 September 2024
Accepted: 17 December 2024

Abstract

When a star dies, it can explode in a supernova, causing a strong shock wave and forming an interstellar object called a supernova remnant (SNR). Observational studies of SNRs allow us to learn about the different types of progenitors, the explosion mechanisms, the physics of interstellar shocks, and the matter cycle in galaxies. We report on the first detection of SNRs located on the outskirts of a galaxy; namely, the Large Magellanic Cloud (LMC), the largest satellite galaxy of our Galaxy. The sources were discovered ∼3° outside the main stellar and gas distribution of the LMC in the recent surveys in radio with the Australian Square Kilometre Array Pathfinder (ASKAP) and in X-rays with the extended Roentgen Survey with an Imaging Telescope Array (eROSITA). We studied them in follow-up observations with the X-ray Multi-Mirror Mission-Newton telescope and MeerKAT and confirmed them to be SNRs. Their progenitors are most likely stars that had left the LMC due to tidal interaction between the Magellanic Clouds and the Milky Way. SNR J0614-7251 is located in an environment with a similar density to those of the other known SNRs in the LMC, and has similar X-ray properties. SNR J0624-6948, on the other hand, is located in a region with a lower density, n₀ < 0.01 cm⁻³. Its radio shell shows a spectral index and polarisation typical of an SNR.