The spectacular “ first light ” observation by the Chandra X-Ray Observatory revealed an X-ray point source near the center of the 300 yr old Cas A supernova remnant .
We present an analysis of the public X-ray spectral and timing data .
No coherent pulsations were detected in the Chandra /HRC data .
The 3 \sigma upper limit on the pulsed fraction is < 35 % for P > 20 ms .
The Chandra /ACIS spectrum of the point source may be fit with an ideal blackbody ( kT =0.5 keV ) , or with blackbody models modified by the presence of a neutron star atmosphere ( kT =0.25–0.35 keV ) , but the temperature is higher and the inferred emitting area lower than expected for a 300 yr old neutron star according to standard cooling models .
The spectrum may also be fit with a power law model ( photon index \Gamma = 2.8 –3.6 ) .
Both the spectral properties and the timing limits of the point source are inconsistent with a young Crab-like pulsar , but are quite similar to the properties of the anomalous X-ray pulsars .
The spectral parameters are also very similar to those of the other radio-quiet X-ray point sources in the supernova remnants Pup A , RCW 103 , and PKS 1209–52 .
Current limits on an optical counterpart for the Cas A point source rule out models that invoke fallback accretion onto a compact object if fallback disk properties are similar to those in quiescent low-mass X-ray binaries .
However , the optical limits are marginally consistent with plausible alternative assumptions for a fallback disk .
In this case , accreting neutron star models can explain the X-ray data , but an accreting black hole model is not promising .