XMM-Newton study of 30 Doradus C and a newly identified MCSNR J0536-6913 in the Large Magellanic Cloud⋆

Abstract

Aims: We present a detailed study of the superbubble 30 Dor C and the newly identified supernova remnant MCSNR J0536-6913 in the Large Magellanic Cloud.
Methods: All available XMM-Newton data (flare-filtered exposure times of 420 ks EPIC-pn, 556 ks EPIC-MOS1, 614 ks EPIC-MOS2) were used to characterise the thermal X-ray emission in the region. An analysis of the non-thermal X-ray emission is also presented and discussed in the context of emission mechanisms previously suggested in the literature. These data are supplemented by X-ray data from Chandra, optical data from the Magellanic Cloud Emission Line Survey, and radio data from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope.
Results: The brightest thermal emission towards 30 Dor C was found to be associated with a new supernova remnant, MCSNR J0536-6913. X-ray spectral analysis of MCSNR J0536-6913 suggested an ejecta-dominated remnant with lines of O, Ne, Mg, and Si, and a total 0.3-10 keV X-ray luminosity of ~8 × 10³⁴ erg s^-1. Based on derived ejecta abundance ratios, we determined the mass of the stellar progenitor to be either ~18 M_⊙ or as high as ≳40 M_⊙, though the spectral fits were subject to simplifying assumptions (e.g., uniform temperature and well-mixed ejecta). The thermal emission from the superbubble exhibited enrichment by α-process elements, evidence for a recent core-collapse SNR interaction with the superbubble shell. We detected non-thermal X-ray emission throughout 30 Dor C, with the brightest regions being highly correlated with the Hα and radio shells. We created a non-thermal spectral energy distribution for the north-eastern shell of 30 Dor C which was best-fit with an exponentially cut-off synchrotron model.
Conclusions: Thermal X-ray emission from 30 Dor C is very complex, consisting of a large scale superbubble emission at the eastern shell wall with the brightest emission due to MCSNR J0536-6913. The fact that the non-thermal spectral energy distribution of the superbubble shell was observed to roll-off is further evidence that the non-thermal X-ray emission from 30 Dor C is synchrotron in origin.

Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.Appendix A is available in electronic form at http://www.aanda.org