EXTENDED EMISSION FROM THE PSR B1259-63/SS 2883 BINARY DETECTED WITH CHANDRA

Alpha PSR B1259-63 is a middle-aged radio pulsar (P = 48 ms, tau = 330 kyr, and (E) over dot = 8.3 x 10(35) erg s(-1)) in an eccentric binary (P-orb = 3.4 yr, e = 0.87) with a high-mass Be companion, SS 2883. We observed the binary near apastron with the Chandra ACTS detector on 2009 May 14 for 28 ks. In addition to the previously studied point-like source at the pulsar's position, we detected extended emission on the south-southwest side of this source. The point-like source spectrum can be described by the absorbed power-law model with the hydrogen column density N-H = (2.5 +/- 0.6) x 10(21) cm(-2), photon index Gamma = 1.6 +/- 0.1, and luminosity L0.5-8 keV approximate to 1.3 x 10(33) d(3)(2) erg s(-1), where d(3) is the distance scaled to 3 kpc. This emission likely includes an unresolved part of the pulsar wind nebula (PWN) created by the colliding winds from the pulsar and the Be companion, and a contribution from the pulsar magnetosphere. The extended emission apparently consists of two components. The highly significant compact component looks like a southward extension of the point-like source image, seen up to similar to 4 '' from the pulsar position. Its spectrum has about the same slope as the point-like source spectrum, while its luminosity is a factor of 10 lower. We also detected an elongated feature extended similar to 15 '' southwest of the pulsar, but the significance of this detection is marginal. We tentatively interpret the resolved compact PWN component as a shocked pulsar wind blown out of the binary by the wind of the Be component, while the elongated component could be a pulsar jet.