[ITAL]Chandra[/ITAL] Discovery of a 100 kiloparsec X-Ray Jet in PKS 0637−752

The quasar PKS 0637-753, the first celestial X-ray target of the ChandraX-ray Observatory, has revealed asymmetric X-ray structure extending from 3 to12 arcsec west of the quasar, coincident with the inner portion of the jetpreviously detected in a 4.8 GHz radio image (Tingay et al. 1998). At aredshift of z=0.651, the jet is the largest (~100 kpc) and most luminous(~10^{44.6} ergs/s) of the few so far detected in X-rays. This letter presentsa high resolution X-ray image of the jet, from 42 ks of data when PKS 0637-753was on-axis and ACIS-S was near the optimum focus. For the inner portion of theradio jet, the X-ray morphology closely matches that of new ATCA radio imagesat 4.8 and 8.6 GHz. Observations of the parsec scale core using the VSOP spaceVLBI mission show structure aligned with the X-ray jet, placing importantconstraints on the X-ray source models. HST images show that there are threesmall knots coincident with the peak radio and X-ray emission. Two of these areresolved, which we use to estimate the sizes of the X-ray and radio knots. Theouter portion of the radio jet, and a radio component to the east, show noX-ray emission to a limit of about 100 times lower flux. The X-ray emission is difficult to explain with models that successfullyaccount for extra-nuclear X-ray/radio structures in other active galaxies. Wethink the most plausible is a synchrotron self-Compton (SSC) model, but thiswould imply extreme departures from the conventional minimum-energy and/orhomogeneity assumptions. We also rule out synchrotron or thermal bremsstrahlungmodels for the jet X-rays, unless multicomponent or ad hoc geometries areinvoked.Comment: 5 Pages, 2 Figures. Submitted to Ap. J. Letter