We clarify the nature of the small-diameter supernova remnant ( SNR ) Kes 73 and its central compact source , 1E 1841 - 045 , using X-ray data acquired with the ASCA Observatory .
We introduce a spatio-spectral decomposition technique necessary to disentangle the ASCA spectrum of the compact source from the barely resolved shell-type remnant .
The source spectrum ( 1 – 8 keV ) is characterized by an absorbed power-law with a photon index \alpha \simeq 3.4 and N _ { H } \simeq 3.0 \times 10 ^ { 22 } cm ^ { -2 } , possibly non-thermal in nature .
This bright X-ray source is likely a slowly spinning pulsar , whose detection is reported in our companion paper ( Vasisht & Gotthelf 1997 ) .
The SNR spectrum is characteristic of a thermal plasma , with kT \simeq 0.7 keV , and emission lines typical of a young remnants .
The element Mg and possibly O and Ne are found to be over-abundant , qualitatively suggesting an origin from a massive progenitor .
We find that Kes 73 is a young ( \lower 2.15 pt \hbox { $ \buildrel < \over { \sim } $ } 2000 yr ) type II/Ib SNR containing a neutron star pulsar spinning anomalously slow for its age .
Kes 73 is yet another member of a growing class of SNRs containing radio-quiet compact sources with a hard spectral signature .