First study of the supernova remnant population in the Large Magellanic Cloud with eROSITA

II. Spectral analysis and X-ray luminosity function

¹ Dr. Karl Remeis Observatory, Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstraße 7, 96049 Bamberg, Germany
² School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
³ Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
⁴ Department of Physics, Maynooth University, Maynooth, Co. Kildare, Ireland
⁵ Australia Telescope National Facility, CSIRO, Space and Astronomy, P.O. Box 76, Epping, NSW 1710, Australia
⁶ Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, 11 rue de l’Universite, 67000 Strasbourg, France
⁷ Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Cassilla 703 La Serena, Chile
⁸ International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
⁹ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
¹⁰ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹¹ Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 October 2025
Accepted: 23 March 2026

Abstract

Aims. Supernova remnants (SNRs) are responsible for the injection of energy and chemical elements into the interstellar medium (ISM). The emission from SNRs can be studied to infer information about the supernova (SN) explosion itself as well as about the properties of the surrounding ISM. Studying a sample of SNRs in a galaxy provides an opportunity to better understand stellar feedback, and the best laboratory for such an investigation is the Large Magellanic Cloud (LMC). The LMC is the nearest star-forming galaxy, it lies outside the Galactic plane line of sight, and therefore its foreground absorption is low.

Methods. The eROSITA telescopes are the best instruments currently available to perform a survey of the SNRs in the entire LMC due to their large field of view and their high sensitivity towards soft X-rays. We used the sample of SNRs reported in the previous paper and performed a spectral analysis on a part of the sample. We estimated the flux and the luminosity of the fainter sources using the energy conversion factor obtained assuming a non-equilibrium ionisation plasma model.

Results. The X-ray luminosity function (XLF) of SNRs in the LMC shows a relatively large number of SNRs at high luminosities. We fitted the distribution with two Gaussian components, which yielded best-fit maxima for the L_X[0.3-8.0keV] distribution at m₁ = 10^34.7±0.2 erg s⁻¹ and m₂ = 10^36.5±0.4 erg s⁻¹. We compared the XLF of the LMC with the XLFs of the Small Magellanic Cloud (SMC), M31, and M33 using a power-law fit and an Anderson-Darling (DA) test. The power indices of the XLFs of the LMC and SMC appear consistent with each other, while those of M33 and M31 are larger. Thus, the latter have steeper power laws, indicating a lower number of X-ray luminous SNRs with respect to the Magellanic Clouds. The DA test showed that the luminosity distributions of SNRs in the SMC and LMC are compatible with being extracted from the same underlying distribution. They are also compatible for different galaxies if we consider the same lower limit for L_X [0.3-8.0 keV] for the entire distribution. Finally, we compared the luminosity and the X-ray sizes (diameter) of the SNRs in our sample. We observed a general trend of anti-correlation between size and X-ray luminosity that can be interpreted as a result of fading with time.