We present the analysis of Chandra X-ray Observatory observations of the eccentric γ-ray binary PSR B1259-63/LS 2883. The analysis shows that the extended X-ray feature seen in previous observations is still moving away from the binary with an average projected velocity of ≈ 0.07c and shows a hint of acceleration. The spectrum of the feature appears to be hard (photon index Γ ≈ 0.8) with no sign of softening compared to previously measured values. We interpret it as a clump of plasma ejected from the binary through the interaction of the pulsar with the decretion disk of the O-star around periastron passage. We suggest that the clump is moving in the unshocked relativistic pulsar wind (PW), which can accelerate the clump. Its X-ray emission can be interpreted as synchrotron radiation of the PW shocked by the collision with the clump. Read more here.
The image shows the false color X-ray image (different colors correspond to different observation epochs) demonstrating the motion and changes in morphology. The dashed line connects the binary and the centroid of the feature in the new data image.