Non--Equilibrium Ionization Effects in the Supernova Remnant RCW 86
Kaastra, J. S.; Smith, A.; Peacock, A.; de Korte, P. A. J.; Claas, J. J.
Netherlands
Abstract
X-ray images show that the SNR RCW 86 consists of two emission regions. The electron temperature of both two regions is 3.4 keV. The low-energy flux (0.2-2 keV) is strongly enhanced compared to a simple thermal bremsstrahlung spectrum with Te = 3.4 keV fitted to the 2-10 keV data. This enhancement is most likely caused by nonequilibrium ionization effects in which case our data of RCW 86 are consistent with a Type I remnant for which the northeast part is in the Sedov phase. The large brightnees of the southwest part is most probably caused by a recent collision of the shock with higher density clouds.