The Compact Central Object in the Supernova Remnant G266.2−1.2

Abstract

We observed the compact central object CXOU J085201.4-461753 in the supernova remnant G266.2-1.2 (RX J0852.0-4622) with the Chandra ACIS detector in timing mode. The spectrum of this object can be described by a blackbody model with the temperature kT = 404 ± 5 eV and radius of the emitting region R = 0.28 ± 0.01 km at a distance of 1 kpc. Power-law and thermal plasma models do not fit the source spectrum. The spectrum shows a marginally significant feature at 1.68 keV. A search for periodicity yields two candidate periods, about 301 and 33 ms, both significant at a 2.1 σ level; the corresponding pulsed fractions are 13% and 9%, respectively. We find no evidence for long-term variability of the source flux, nor do we find extended emission around the central object. We suggest that CXOU J085201.4-461753 is similar to CXOU J232327.9+584842, the central source of the supernova remnant Cas A. It could be either a neutron star with a low or regular magnetic field, slowly accreting from a fossil disk or, more likely, an isolated neutron star with a superstrong magnetic field. In either case, a conservative upper limit on surface temperature of a 10 km radius neutron star is about 90 eV, which suggests accelerated cooling for a reasonable age of a few thousand years.