Powering Anomalous X-Ray Pulsars by Neutron Star Cooling

Using recently calculated analytic models for the thermal structure of ultramagnetized neutron stars, we estimate the thermal fluxes from young ( t ~1000 yr) ultramagnetized ( B ~10 15 G) cooling neutron stars. We find that the pulsed X-ray emission from objects such as 1E 1841-045 and 1E 2259+586, as well as many soft-gamma repeaters, can be explained by photon cooling if the neutron star possesses a thin insulating envelope of matter of low atomic weight at densities ρ<10 7 -10 8 g cm −3 . The total mass of this insulating layer is M ~10 −11 -10 −8 M ☉ .