X-Ray Emission from the Nearby PSR B1133+16 and Other Old Pulsars

We detected a nearby (d ≃ 360 pc), old (τ ≃ 5 Myr) pulsar B1133+16 with Chandra. The observed pulsar's flux is (0.8 ± 0.2) × 10-14 ergs cm-2 s-1 in the 0.5-8 keV band. Because of the small number of counts detected, the spectrum can be described by various models. A power-law fit of the spectrum gives a photon index Γ ≈ 2.5 and an isotropic luminosity of 1.4 × 1029 ergs s-1 in the 0.5-8 keV band, which is about 1.6 × 10-3 of the spin-down power . The spectrum can also be fitted by a blackbody model with a temperature of ≈2.8 MK and a projected emitting area of ~500 m2, possibly a hot polar cap. The X-ray properties of PSR B1133+16 are similar to those of other old pulsars observed in X-rays, particularly the drifting pulsar B0943+10.