The radial structure of supernova remnant N103b

We report on the results from a Chandra ACIS observation of the young, compact, supernova remnant N103B. The unprecedented spatial resolution of Chandra reveals subarcsecond structure, in both the brightness and spectral variations. Underlying these small-scale variations is a surprisingly simple radial structure in the equivalent widths of the strong Si and S emission lines. We investigate these radial variations through spatially resolved spectroscopy, using a plane-parallel, nonequilibrium ionization model with multiple components. The majority of the emission arises from components with a temperature of 1 keV: a fully ionized hydrogen component; a high ionization timescale (n_et > 10¹² s cm^-3) component containing Si, S, Ar, Ca, and Fe; and a low ionization timescale (n _et ∼ 10¹¹ s cm^-3) O, Ne, and Mg component. To reproduce the strong Fe Kα line, it is necessary to include additional Fe in a hot (> 2 keV), low ionization timescale (n_et ∼ 10 ^10.8 s cm^-3) component. This hot Fe might be in the form of hot Fe bubbles, formed in the radioactive decay of clumps of ⁵⁶Ni. We find no radial variation in the ionization timescales or temperatures of the various components. Rather, the Si and S equivalent widths increase at large radii because these lines, as well as those of Ar and Ca, are formed in a shell occupying the outer half of the remnant. A shell of hot Fe is located interior to this, but there is a large region of overlap between these two shells. In the inner 30% of the remnant, there is a core of cooler, 1 keV Fe. We find that the distribution of the ejecta and the yields of the intermediate-mass species are consistent with model prediction for Type la events.