Chandra Observations of a New Supernova Remnant AX J1843.8-0352/G28.6-0.1

AX J1843.8-0352 is a new X-ray SNR identified to the radio complex G28.6-0.1 with the ASCA satellite. Chandra discovered two distinct components from this SNR: non-thermal and thin thermal X-ray emissions. The non-thermal component is fitted with a power-law spectrum of photon index 2.0. The morphology is complicated, but roughly an elliptical shape with a mean diameter of about 7'-10'. The east to south rims of the ellipse are associated with the non-thermal radio sources C, F and G (Helfand et al. 1989). The power-law slope of the radio spectrum can be smoothly connected to that of X-rays with a break at around the optical-IR band, hence would be due to synchrotron X-rays accelerated probably to > 1 TeV at the shell of the SNR. The thermal component near the southeast rim is a thin plasma of about 0.8 keV temperature. It has the appearance of a "Tadpole" figure with a head of 30"x 40"-size and a tail of 30"-long. Although this emission is associated with the west part of the radio source F, the absorption is about two times larger than that of the non-thermal X-rays, the bulk of the SNR emission. Therefore, together with the peculiar morphology, whether the thermal plasma is a part of the SNR or a background object is unclear.