Multiwavelength study of the newly confirmed supernova remnant MCSNR J0527-7104 in the Large Magellanic Cloud

Abstract

The Large Magellanic Cloud (LMC) hosts a rich and varied population of supernova remnants (SNRs). Optical, X-ray, and radio observations are required to identify these SNRs, as well as to ascertain the various processes responsible for the large array of physical characteristics observed. In this paper we attempted to confirm the candidate SNR [HP99] 1234, identified in X-rays with ROSAT, as a true SNR by supplementing these X-ray data with optical and radio observations. Optical data from the Magellanic Cloud Emission Line Survey (MCELS) and new radio data from the Molonglo Observatory Synthesis Telescope (MOST), in addition to the ROSAT X-ray data, were used to perform a morphological analysis of this candidate SNR. An approximately ellipsoidal shell of enhanced [SII], typical of an SNR ([SII]/Halpha > 0.4), was detected in the optical. This enhancement is coincident with faint radio emission at 36 cm. Using the available data we estimated the size of the remnant to be ~5.1' x 4.0' (~75 pc x 59 pc). However, the measurement along the major-axis was somewhat uncertain due to a lack of optical and radio emission at its extremities and the poor resolution of the X-ray data. Assuming this SNR is in the Sedov phase and adopting the ambient mass density of 1.2x10^-25 g cm^-3 measured in a nearby HII region, an age estimate of ~25 kyr was calculated for a canonical initial explosion energy of 10^51 erg. However, this age estimate should be treated cautiously due to uncertainties on the adopted parameters. Analysis of the local stellar population suggested a type Ia event as a precursor to this SNR, however, a core-collapse mechanism could not be ruled out due to the possibility of the progenitor being a runaway massive star. With the detection of X-ray, radio and optical line emission with enhanced [SII], this object was confirmed as an SNR and we assign the identifier MCSNR J0527-7104.