X-Ray Detection of Pulsar PSR B1757−24 and Its Nebular Tail

We report the first X-ray detection of the radio pulsar PSR B1757-24 usingthe Chandra X-ray Observatory. We detect point-source emission at the pulsarposition plus a faint tail extending nearly 20" east of the pulsar, in the samedirection and with comparable morphology to the radio tail. Assuming thepoint-source X-ray emission is magnetospheric, the observed X-ray tailrepresents only ~0.01% of the pulsar's spin-down luminosity. This issignificantly lower than the analogous efficiencies of most known X-ray nebulaesurrounding rotation-powered pulsars. Assuming a non-thermal spectrum for thetail photons, we show that the tail is unlikely to be emission left behindfollowing the passage of the pulsar, but rather is probably fromsynchrotron-emitting pulsar wind particles having flow velocity ~7000 km/s. Wealso show that there must be a significant break in the tail synchrotronspectrum between the radio and X-ray bands that is intrinsic to the particlespectrum. No emission is detected from the shell supernova remnant G5.4-1.2.The upper limits on remnant emission are unconstraining.Comment: Updated Journal ref, corrected typo for flow velocit