XMM-Newton large programme on SN1006 - II. Thermal emission

Abstract

Based on the XMM-Newton large programme on SN1006 and our newly developed tools for spatially resolved spectroscopy analysis as described in Li et al. (Paper I), we study the thermal emission from interstellar medium (ISM) and ejecta of SN1006 by analysing the spectra extracted from 583 tessellated regions dominated by thermal emission. With some key improvements in spectral analysis as compared to Paper I, we obtain much better spectral fitting results with significantly less residuals. The spatial distributions of the thermal and ionization states of the ISM and ejecta show significantly different features, which are in general consistent with a scenario that the ISM (ejecta) is heated and ionized by the forward (reverse) shock propagating outward (inward). Different heavy elements show different spatial distributions so different origins, with Ne mostly from the ISM, Si and Smostly from the ejecta, and O and Mg from both the ISM and ejecta. Fe L-shell line emissions are only detected in a small shell-like region south-east (SE) to the centre of SN1006, indicating that most of the Fe-rich ejecta has not yet or just recently been reached by the reverse shock. The overall abundance patterns of the ejecta for most of the heavy elements, except for Fe and sometimes for S, are consistent with typical Type Ia SN products. The north-west (NW) half of the supernova remnant interior between theNWshell and the soft X-ray brighter SE half probably represents a region with turbulently mixed ISM and ejecta, so has enhanced emission from O, Mg, Si, and S, lower ejecta temperature, and a large diversity of ionization age. In addition to the asymmetric ISM distribution, an asymmetric explosion of the progenitor star is also needed to explain the asymmetric ejecta distribution.