Multifrequency study of a new Fe-rich supernova remnant in the Large Magellanic Cloud, MCSNR J0508−6902

Abstract

We present a detailed radio, X-ray and optical study of a newly discovered Large Magellanic Cloud (LMC) supernova remnant (SNR) which we denote as MCSNR J0508-6902. Observations from the Australia Telescope Compact Array (ATCA) and the XMM-Newton X-ray observatory are complemented by deep H images and Anglo-Australian Telescope AAOmega spectroscopic data to study the SNR shell and its shock ionization. Archival data at other wavelengths are also examined. The remnant follows a filled-in shell-type morphology in the radio continuum and has a size of 74 pc 57 pc at the LMC distance. The X-ray emission exhibits a faint soft shell morphology with Fe-rich gas in its interior -indicative of a Type Ia origin. The remnant appears to be mostly dissipated at higher radio-continuum frequencies leaving only the south-eastern limb fully detectable while in the optical it is the western side of the SNR shell that is clearly detected. The best-fitting temperature to the shell X-ray emission (kT = 0.41 +0.05 -0.06 keV) is consistent with other large LMC SNRs. We determined an O/Fe ratio of <21 and an Fe mass of 0.5-1.8 M in the interior of the remnant, both of which are consistent with the Type Ia scenario. We find an equipartition magnetic field for the remnant of 28 G, a value typical of older SNRs and consistent with other analyses which also infer an older remnant.