2014ApJ...781...41K

We present a Chandra and XMM-Newton study of the supernova remnant (SNR) Kes 73 hosting the anomalous X-ray pulsar 1E 1841-045. The Chandra image reveals clumpy structures across the remnant with enhanced emission along the western rim. The X-ray emission fills the radio shell and spatially correlates with the infrared image. The global X-ray spectrum is described by a two-component thermal model with a column density N_H= 2.6_–0.3^+0.410²²/cm2 and a total luminosity of L_X= 3.3_–0.5^+0.710³⁷ erg/s (0.5-10 keV, at an assumed distance of 8.5 kpc). The soft component is characterized by a temperature kT_s= 0.5_–0.2^+0.1 keV, a high ionization timescale, and enhanced Si and S abundances, suggesting emission that is dominated by shocked ejecta. The hard component has a temperature kT_h= 1.6_–0.7^+0.8 keV, a relatively low ionization timescale, and mostly solar abundances suggesting emission that is dominated by interstellar/circumstellar shocked material. A spatially resolved spectroscopy study reveals no significant variations in the spectral properties. We infer an SNR age ranging between 750 yr and 2100 yr, an explosion energy of 3.0_-1.8^+2.8 x 10⁵⁰ erg and a shock velocity of (1.2±0.3)x10³ km/s (under the Sedov phase assumption). We also discuss the possible scenario for Kes 73 expanding into the late red-supergiant wind phase of its massive progenitor. Comparing the inferred metal abundances to core-collapse nucleosynthesis model yields, we estimate a progenitor mass ≳ 20 M_☉, adding a candidate to the growing list of highly magnetized neutron stars proposed to be associated with very massive progenitors.