Detection of the neutral iron line from the supernova remnant W 49 B with Suzaku

Abstract

Recent studies of supernova remnants (SNRs) have revealed that some SNRs exhibit a neutral iron line emission at 6.4 keV. This line has been proposed to originate from the interaction of high-energy particles formed in the SNR shell with the surrounding cold matter. We searched for the neutral iron line emission in the SNR W 49 B. Significant detection of the 6.4 keV line is found in the north-west region, close to the molecular cloud interacting with the SNR shell. In addition, an excess emission at 8–9 keV, in which Kγ, Kδ, and Kϵ lines of He-like iron exist, is also significantly found in the region where the radio shell is not bright. We discuss the origin of the 6.4 keV line and the excess emission at 8–9 keV.