Exploring the X-ray emission properties of the supernova remnant G67.7+1.8 and its central X-ray sources

Abstract

We have studied the supernova remnant G67.7+1.8 with the Chandra X-ray observatory. The remnant's X-ray morphology correlates well with the double-arc structure seen at radio wavelength. The X-ray spectra of the northern and southern rim of G67.7+1.8 exhibit emission line features of highly ionized metals, which suggests that most of the observed X-rays originate in a thermal plasma. We find magnesium, silicon, and sulphur are overabundant relative to the solar values. Gaussian emission lines at $\sim 4$ keV and $\sim 7$ keV are detected. The $\sim 4$ keV line is consistent with K-emission lines from ${}^{44}$Ca and/or ${}^{44}$Sc whereas the $\sim 7$ keV line feature may arise from unresolved Fe-K lines. Chandra's sub-arcsecond angular resolution allowed us to detect four faint point sources located within $\sim 1.5$ arc-minutes of the geometrical remnant center. Among these objects, CXOU195424.75+312824.9 and CXOU195429.82+312834.1 do not have optical counterparts, leaving them as candidates for a possible compact stellar remnant.

Accepted by A&A, 10 pages, 6 figures, 3 tables