We consider the nature of the elusive neutron star candidate 1E 161348 - 5055 using X-ray observations obtained with the ASCA Observatory .
The compact X-ray source is centered on the shell-type Galactic supernova remnant RCW 103 and has been interpreted as a cooling neutron star associated with the remnant .
The X-ray spectrum of the remnant shell can be characterized by a non-equilibrium ionization ( NEI ) thermal model for a shocked plasma of temperature kT \sim 0.3 keV .
The spectrum falls off rapidly above 3 keV to reveal a point source in the spectrally-resolved images , at the location of 1E 161348 - 5055 .
A black-body model fit to the source spectrum yields a temperature kT = 0.6 keV , with an unabsorbed 0.5–10 keV luminosity of L _ { X } \sim 10 ^ { 34 } erg s ^ { -1 } ( for an assumed distance of 3.3 kpc ) , both of which are at least a factor of 2 higher than predicted by cooling neutron star models .
Alternatively , a power-law model for the source continuum gives a steep photon index of \alpha \sim 3.2 , similar to that of other radio-quiet , hard X-ray point sources associated with supernova remnants .
1E 161348 - 5055 may be prototypical of a growing class of radio-quiet neutron stars revealed by ASCA ; we suggest that these objects account for previously hidden neutron stars associated with supernova remnants .