DISCOVERY OF X-RAY PULSATIONS FROM THE INTEGRAL SOURCE IGR J11014-6103

We report the discovery of PSR J1101-6101, a 62.8 ms pulsar in IGR J11014-6103, a hard X-ray source with a jet and a cometary tail that strongly suggests it is moving away from the center of the supernova remnant (SNR) MSH 11-61A at v > 1000 km s(-1). Two XMM-Newton observations were obtained with the EPIC pn in small window mode, resulting in the measurement of its spin-down luminosity E = 1.36 x 10(36) erg s(-1), characteristic age tau(c) = 116 kyr, and surface magnetic field strength B-s = 7.4 x 10(11) G. In comparison to tau(c) the 10-30 kyr age estimated for MSH 11-61A suggests that the pulsar was born in the SNR with initial period in the range 54 <= P-0 <= 60 ms. PSR J1101-6101 is the least energetic of the 15 rotation-powered pulsars detected by INTEGRAL, and has a high efficiency of hard X-ray radiation and jet power. We examine the shape of the cometary nebula in a Chandra image, which is roughly consistent with a bow shock at the velocity inferred from the SNR age and the pulsar's E. However, its structure differs in detail from the classic bow shock, and we explore possible reasons for this.