MSHÂ 15–5 6 ( G326.3-1.8 ) is a composite supernova remnant ( SNR ) that consists of an SNR shell and a displaced pulsar wind nebula ( PWN ) in the radio .
We present XMM-Newton and Chandra X-ray observations of the remnant that reveal a compact source at the tip of the radio PWN and complex structures that provide evidence for mixing of the supernova ( SN ) ejecta with PWN material following a reverse shock interaction .
The X-ray spectra are well fitted by a non-thermal power-law model whose photon index steepens with distance from the presumed pulsar , and a thermal component with an average temperature of 0.55 keV .
The enhanced abundances of silicon and sulfur in some regions , and the similar temperature and ionization timescale , suggest that much of the X-ray emission can be attributed to SN ejecta that have either been heated by the reverse shock or swept up by the PWN .
We find one region with a lower temperature of 0.3 keV that appears to be in ionization equilibrium .
Assuming the Sedov model , we derive a number of SNR properties , including an age of 16,500 yr .
Modeling of the \gamma -ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN .