Diprotodon on the sky. The Large Galactic Supernova Remnant (SNR) G278.94+1.35

Filipović MD, Lazarević S, Araya M, Hurley-Walker N, Kothes R, Sano H, Rowell G, Martin P, Fukui Y, Alsaberi RZ, Arbutina B, Ball B, Bordiu C, Brose R, Bufano F, Burger-Scheidlin C, Anne Collins T, Crawford EJ, Dai S, William Duchesne S, Fuller R, Hopkins A, Ingallinera A, Inoue H, Jarrett T, Silvia Koribalski B, Leahy D, Luken K, Mackey J, Macgregor P, Norris R, Payne J, Riggi S, Riseley C, Sasaki M, Smeaton Z, Sushch I, Stupar M, Umana G, Urošević D, Velović V, Vernstrom T, Vukotić B, West J (2024)

Publication Type: Journal article, Review article

Publication year: 2024

Journal

Book Volume: 41

Article Number: e112

DOI: 10.1017/pasa.2024.93

Abstract

We present a re-discovery of G278.94+1.35^a as possibly one of the largest known Galactic supernova remnants (SNRs) - that we name Diprotodon. While previously established as a Galactic SNR, Diprotodon is visible in our new Evolutionary Map of the Universe (EMU) and GaLactic and Extragalactic All-sky MWA (GLEAM) radio continuum images at an angular size of, much larger than previously measured. At the previously suggested distance of 2.7 kpc, this implies a diameter of 157 152 pc. This size would qualify Diprotodon as the largest known SNR and pushes our estimates of SNR sizes to the upper limits. We investigate the environment in which the SNR is located and examine various scenarios that might explain such a large and relatively bright SNR appearance. We find that Diprotodon is most likely at a much closer distance of 1 kpc, implying its diameter is 58 56 pc and it is in the radiative evolutionary phase. We also present a new Fermi-LAT data analysis that confirms the angular extent of the SNR in gamma rays. The origin of the high-energy emission remains somewhat puzzling, and the scenarios we explore reveal new puzzles, given this unexpected and unique observation of a seemingly evolved SNR having a hard GeV spectrum with no breaks. We explore both leptonic and hadronic scenarios, as well as the possibility that the high-energy emission arises from the leftover particle population of a historic pulsar wind nebula.

Authors with CRIS profile

Involved external institutions

University of Western Sydney Australia (AU) Universidad de Costa Rica Costa Rica (CR) International Centre for Radio Astronomy Research Australia (AU) National Research Council / Conseil national de recherches Canada Canada (CA) Gifu University / 岐阜大学 Japan (JP) University of Adelaide Australia (AU) Institut de Recherche en Astrophysique et Planétologie (IRAP) France (FR) Nagoya University / 名古屋大学 Japan (JP) University of Belgrade / Универзитет у Београду Serbia (RS) University of Alberta Canada (CA) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) Dublin City University (DCU) Ireland (IE) DIAS Dunsink Observatory Ireland (IE) Universität Potsdam Germany (DE) Commonwealth Scientific and Industrial Research Organisation (CSIRO) Australia (AU) Macquarie University Australia (AU) University of Calgary Canada (CA) University of Bologna / Università di Bologna Italy (IT) Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) Spain (ES) University of Western Australia (UWA) Australia (AU) Astronomical Observatory Belgrade Serbia (RS)

How to cite

APA:

Filipović, M.D., Lazarević, S., Araya, M., Hurley-Walker, N., Kothes, R., Sano, H.,... West, J. (2024). Diprotodon on the sky. The Large Galactic Supernova Remnant (SNR) G278.94+1.35. Publications of the Astronomical Society of Australia, 41. https://doi.org/10.1017/pasa.2024.93

MLA:

Filipović, Miroslav D., et al. "Diprotodon on the sky. The Large Galactic Supernova Remnant (SNR) G278.94+1.35." Publications of the Astronomical Society of Australia 41 (2024).

BibTeX: Download