We present X-ray images of Tycho ’ s supernova remnant in emission line features of Mg , Si , S , Ar , Ca , and Fe , plus the continuum , using data obtained by the imaging spectrometers onboard the ASCA X-ray satellite .
All the images show the shell-like morphology characteristic of previously obtained broad-band X-ray images , but are clearly distinct from each other .
We use image reconstruction techniques to achieve a spatial resolution of \sim 0.8 ^ { \prime } .
Line intensity ratios are used to make inferences about the remnant ’ s physical state , on average for the entire remnant , and with angular position around the rim .
The average temperature of the Si and S ejecta in the remnant is ( 0.8 - 1.1 ) \times 10 ^ { 7 } K and the average ionization age is ( 0.8 - 1.3 ) \times 10 ^ { 11 } cm ^ { -3 } s. For a constant ionization age , the observed relative brightness variations of Si and S line image profiles with azimuthal angle imply differences of roughly a factor of 1.3 - 1.8 in the temperature .
We compare the radial brightness profiles of our images to simple geometrical models , and find that a spherical emitting geometry is favored over a torus .
A spherical geometry is further supported by the absence of systematic Doppler shifts across the remnant .
The radial fit results also suggest that some radial mixing of the ejecta has occurred .
However , the azimuthally averaged Fe K image peaks at a markedly lower radius than the other images .
The average Fe K/Fe L line intensity ratio and the position of the Fe K energy centroid support a temperature several times higher and an ionization age approximately a factor of ten lower than for the other elements , and imply that the Fe ejecta must have retained some of its stratification .
Although many of the features in the 4 - 6 keV X-ray continuum correspond to those in the radio , there is no obvious correlation between the relative brightness in these bands .