Chandra Observations of the Pulsar B1929+10 and Its Environment

We report on two Chandra observations of the 3 Myr old pulsar B1929+10, which reveal a faint compact (~9^'' × 5^'') nebula elongated in the direction perpendicular to the pulsar's proper motion, two patchy wings, and a possible short (~3^'') jet emerging from the pulsar. In addition, we detect a tail extending up to at least 4^' in the direction opposite to the pulsar's proper motion, aligned with the ~15^' long tail detected in ROSAT and XMM-Newton observations. The overall morphology of the nebula suggests that the shocked pulsar wind is confined by the ram pressure due to the pulsar's supersonic speed. The shape of the compact nebula in the immediate vicinity of the pulsar seems to be consistent with the current MHD models. However, since these models do not account yet for the change of the flow velocity at larger distances from the pulsar, they are not able to constrain the extent of the long pulsar tail. The luminosity of the whole nebula as seen by Chandra is L_PWN ~ 10³⁰ ergs s^-1 in the 0.3-8 keV band, for the distance of 361 pc. Using the Chandra and XMM-Newton data, we found that the pulsar spectrum is composed of nonthermal (magnetospheric) and thermal components. The nonthermal component can be described by a power-law model with photon index Γ ≈ 1.7 and luminosity L^nonth_PSR ≈ 1.7 × 10³⁰ ergs s^-1 in the 0.3-10 keV band. The blackbody fit for the thermal component, which presumably emerges from hot polar caps, gives the temperature kT ≈ 0.3 keV and projected emitting area A_⊥ ~ 3 × 10³ m², corresponding to the bolometric luminosity L_bol ~ (1-2) × 10³⁰ ergs s^-1.