We present the results of broadband spectral model fits to the X-ray spectrum of Tycho ’ s supernova remnant obtained by the Solid-State Imaging Spectrometers on the ASCA Observatory .
We use single-temperature , single-ionization-age , nonequilibrium ionization models to characterize the ejecta and the blast-shocked interstellar medium .
Previous spectral studies have suggested that the Fe ejecta in this Type Ia remnant are stratified interior to the other ejecta .
These studies , however , have generally restricted their attention to the Fe K blend at 6.5 keV .
ASCA provides data over a broad energy range that allow the placement of important constraints simultaneously from the Fe L emission near 1 keV as well as the Fe K emission .
We find that the simplest models , with emission from the ejecta and blast wave each at a single temperature and ionization age , severely underestimate the flux in the Fe K blend .
These models also show that there is little Fe emission associated with the Si and S ejecta shell , which has an average temperature kT \sim 0.86 keV and ionization age n _ { e } t \sim 10 ^ { 11 } cm ^ { -3 } s. The blast-shocked interstellar medium has abundances roughly 0.3 times the solar value , while the ejecta , with the exception of Fe , have relative abundances that are typical of Type Ia supernovae .
The addition of another component of Fe emission , which we associate with ejecta , at a temperature at least two times higher and an ionization age \sim 100 times lower than the Si ejecta , does provide a good fit to the spectrum .
This model is consistent with imaging results .
Although fluorescent emission from dust in the remnant may contribute to the Fe K flux , we conclude that it is unlikely to be the dominant component .