X-ray observations of the supernova remnant W44

Abstract

We present Einstein Observatory X-ray observations of the supernova remnant W44 (G34.7-0.4). The X-ray morphology is centrally peaked and shows an anti-correlation with the radio shell. X-ray spectral data indicate a temperature for the emitting plasma of approximately 1 keV. We suggest a model for W44 in which the remnant is in its late adiabatic phase. The soft X-ray shell has become too cool to be observable through the intervening ISM, yet a hotter interior remains visible. W44 would then appear to fit in reasonably well with the generally accepted evolution of shell-like remnants and a Crab-like component is not required to explain the X-ray morphology.