ChandraDetection of Ejecta in the Small‐Diameter Supernova Remnant G349.7+0.2

Abstract

We present high-resolution X-ray observations of the small-diameter supernova remnant (SNR) G349.7+0.2 with Chandra. The overall SNR spectrum can be described by two spectral components. The soft component is in ionization equilibrium and has a temperature of ?0.8?keV; the hard spectral component has a temperature of ?1.4?keV, an ionization timescale of ?5 ? 1011?cm-3 s, and enhanced abundances of Si. The spatially resolved spectral modeling shows that S may also be enhanced, at least in some regions. The enhanced abundances clearly point to the presence of an ejecta component in this remnant. Using the available H I and CO data toward G349.7+0.2 we derive a column density of ?7 ? 1022?cm-2 along the line of sight to the SNR, which is consistent with our X-ray data. The X-ray morphology of G349.7+0.2 is strikingly similar to that at radio wavelengths?an irregular shell with a brighter eastern side?which is consistent with expansion in a medium with a large-scale density gradient. The remnant is known to be interacting with a molecular cloud (from the presence of OH (1720?MHz) masers), but this interaction is probably limited to the central portion of the SNR, as seen in SNR IC?443. We found that H I clouds are present in the SNR region, which supports the notion that G349.7+0.2 belongs to a class of remnants evolving in the intercloud medium (such are IC?443 and W44), which is also responsible for the remnant's morphology. G349.7+0.2 does not have the mixed-morphology found for other maser-emitting SNRs studied to date in X-rays, but its morphology can be explained by a projection model for mixed-morphology SNRs. We have identified a point source close to the center of the SNR with a luminosity of LX(0.5-10.0 keV) ~ (0.2-2.3) ? 1034?d22?ergs s-1, which is consistent with that of the compact central objects found in a few other Galactic SNRs.