Multi-frequency study of the newly confirmed supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud

TL;DR

This study characterizes the supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud across multiple wavelengths, revealing its morphology, magnetic field, and unusual X-ray emission, suggesting a wind-blown cavity origin and a possible core-collapse supernova.

Contribution

First multi-frequency detailed analysis of MCSNR J0512-6707, combining X-ray, radio, and infrared data to understand its morphology, magnetic field, and emission components, proposing a wind-blown cavity origin.

Findings

Remnant size estimated at 24.9 x 21.9 pc with a 29° major axis rotation.

Radio polarization indicates magnetic field compression by the shock front.

X-ray spectrum shows a soft thermal component and an unclear hard component.

Abstract

We present a study of the supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud. We used new data from XMM-Newton to characterise the X-ray emission and data from the Australian Telescope Compact Array, the Magellanic Cloud Emission Line Survey, and Spitzer to gain a picture of the environment into which the remnant is expanding. We performed a morphological study, determined radio polarisation and magnetic field orientation, and performed an X-ray spectral analysis. We estimated the its size to be 24.9 (\pm1.5) x 21.9 (\pm1.5) pc, with the major axis rotated ~29 deg east of north. Radio polarisation at 3 cm and 6 cm indicate a higher degree of polarisation in the NW and SE tangentially oriented to the SNR shock front, indicative of an SNR compressing the magnetic field threading the interstellar medium. The X-ray spectrum is unusual as it requires a soft (~0.2 keV) CIE thermal plasma of interstellar medium abundance, in addition to a harder component. Using our results and the Sedov dynamical model, we showed that this emission is not consistent with a Sedov remnant. We suggested that the thermal X-rays can be explained by MCSNR J0512-6707 having initially evolved into a wind-blown cavity and is now interacting with the surrounding dense shell. The origin of the hard component remains unclear. We could not determine the supernova type from the X-ray spectrum. Indirect evidence was found in the study of the local stellar population and star formation history in the literature, which suggests a core-collapse origin. MCSNR J0512-6707 likely resulted from the core-collapse of high mass progenitor which carved a low density cavity into its surrounding medium, with the soft X-rays resulting from the impact of the blast wave with the surrounding shell. The unusual hard X-ray component requires deeper and higher spatial resolution radio and X-ray observations to confirm its origin.