X‐Ray Emission from the Radio‐quiet Neutron Star in Puppis A

Abstract

We show that X-rays detected with the ROSAT andASCA observatories from the radio-quiet neutron star candidate RXJ0822-4300 in the Puppis A supernova remnant can be interpreted asradiation from a hydrogen or helium neutron star atmosphere. Fittingthe observed X-ray spectra with the atmosphere models gives morerealistic values for the effective temperatures and emitting areasthan the commonly used blackbody model. The temperature obtained,T &infy; eff =(1.6-1.9)x10 6 K, is consistentwith the standard neutron star cooling models. The correspondingdistance and hydrogen column density are in good agreement with thoseobtained from independent estimates. Timing analysis of the combinedresults of the ROSAT PSPC and HRI observations separated by 4.6 yrenabled us to co-align phases of pulse profiles and find more accurateephemeris parameters of this putative 75 ms isolated X-ray pulsar.