New Identification of the Mixed-Morphology Supernova Remnant G298.6-0.0 with Possible Gamma-Ray Association

We present an X-ray analysis on the Galactic supernova remnant (SNR) G298.6−0.0 observed with Suzaku. The X-ray image shows a center-filled structure inside a radio shell, implying that this SNR can be categorized as a mixed-morphology (MM) SNR. The spectrum is well reproduced by a single-temperature plasma model in ionization equilibrium, with a temperature of 0.78 (0.70-0.87) keV. The total plasma mass of 30M indicates that the plasma has an interstellar medium origin. The association with a GeV gamma-ray source, 3FGL J1214.0−6236, on the shell of the SNR is discussed, in comparison with other MMSNRs with GeV gamma-ray associations. It is found that the flux ratio between absorption-corrected thermal X-rays and GeV gamma-rays decreases as the physical size of MMSNRs becomes larger. The absorption-corrected thermal X-ray flux of G298.6−0.0 and the GeV gamma-ray flux of 3FGL J1214.0−6236 closely follow this trend, implying that 3FGL J1214.0−6236 is likely to be a GeV counterpart of G298.6−0.0.