[Previous] | [Session 43] | [Next]
G.G. Pavlov (Penn State), V.E. Zavlin, J. Tr\"umper (MPE, Garching)
We show that X-rays detected with the ROSAT and ASCA observatories from the radio-quiet neutron star candidate RX~J0822--4300 in the Puppis A supernova remnant can be interpreted as radiation from a hydrogen or helium neutron star atmosphere. Fittting the observed X-ray spectra with the atmosphere models gives more realistic values for the effective temperatures and radiating areas than the commonly used blackbody model. The temperature obtained, T\rm eff\infty =(1.6-1.8)\times 106~K, is consistent with the standard neutron star cooling models. The corresponding distance and hydrogen column density are in good agreement with those obtained from independent estimates.
We also searched for pulsations of the X-ray flux from this object. An analysis of two ROSAT observations separated by 4.56~yr enabled us to find a period P~q 75.3~ms and its derivative \dot{P}~q 1.49\times 10-13~s~s-1. The corresponding characteristic parameters of the neutron star, age \tau=P/(2\dot{P}) = 8.0~kyr, magnetic field B=3.4\times 1012~G, and rotational energy loss \dot{E}=1.4\times 1037~erg~s-1, are typical for young radio pulsars. These results indicate that RX~J0822--4300 is a rotating magnetized neutron star whose radio flux is not seen because of an unfavorable orientation of the pulsar beam. Since the X-ray radiation has a thermal-like spectrum, its pulsations may be due to a nonuniform temperature distribution over the neutron star surface caused by anisotropy of the heat conduction in the strongly magnetized crust.
The author(s) of this abstract have provided an email address for comments about the abstract: pavlov@astro.psu.edu