The X-ray Properties of Five Galactic Supernova Remnants Detected by the Spitzer GLIMPSE Survey
We present a study of the X-ray properties of five Galactic supernova remnants (SNRs)—Kes 17 (G304.6 + 0.1), G311.5−0.3, G346.6−0.2, CTB 37A (G348.5 + 0.1), and G348.5−0.0—that were detected in the infrared by Reach et al. in an analysis of data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer Space Telescope. We present and analyze archival ASCA observations of Kes 17, G311.5−0.3, and G346.6−0.2, archival XMM-Newton observations of Kes 17, CTB 37A, and G348.5−0.0, and an archival Chandra observation of CTB 37A. All of the SNRs are clearly detected in the X-ray except possibly G348.5−0.0. Our study reveals that the four detected SNRs all feature center-filled X-ray morphologies and that the observed emission from these sources is thermal in all cases. We argue that these SNRs should be classified as mixed morphology SNRs (MM SNRs); our study strengthens the correlation between MM SNRs and SNRs interacting with molecular clouds and suggests that the origin of MM SNRs may be due to the interactions between these SNRs and adjacent clouds. Our ASCA analysis of G311.5−0.3 reveals for the first time X-ray emission from this SNR: the X-ray emission is center-filled within the radio and infrared shells and thermal in nature (kT ∼ 0.98 keV), thus motivating its classification as an MM SNR. We find considerable spectral variations in the properties associated with the plasmas of the other X-ray-detected SNRs, such as a possible overabundance of magnesium in the plasma of Kes 17. Our new results also include the first detailed spatially resolved spectroscopic study of CTB 37A using Chandra as well as a spectroscopic study of the discrete X-ray source CXOU J171428.5−383601, which may be a neutron star associated with CTB 37A. Finally, we also estimate such properties as electron density ne, radiative age trad and swept-up mass MX for each of the four X-ray-detected SNRs. Each of these values are comparable to archetypal MM SNRs like 3C 391 and W44. In an analysis of the spectrum of Kes 17, we did not find evidence of over-ionization unlike other archetypal MM SNRs like W44 and W49B.
The Astronomical Journal, 147:55 (34pp), 2014 March.