Direct measurement of neutron star recoil in the oxygen-rich supernova remnant Puppis A

A sequence of three Chandra X-Ray Observatory High Resolution Camera images taken over a span of five years reveals arcsecond-scale displacement of RX J0822-4300, the stellar remnant ( presumably a neutron star) near the center of the Puppis A supernova remnant. We measure its proper motion to be 0.165 +/- 0.025 yr(-1) toward the west-southwest. At a distance of 2 kpc, this corresponds to a transverse space velocity of similar to 1600 km s(-1). The space velocity is consistent with the explosion center inferred from proper motions of the oxygen-rich optical filaments and confirms the idea that Puppis A resulted from an asymmetric explosion accompanied by a kick that imparted roughly 3 x 10(49) ergs of kinetic energy (some 3% of the kinetic energy for a typical supernova) to the stellar remnant. We discuss constraints on core-collapse supernova models that have been proposed to explain neutron star kick velocities.