2003ApJ...591L.139H

We report the discovery of pulsed X-ray emission from the compact object CXOU J112439.1-591620 within the supernova remnant G292.0+1.8 using the High Resolution Camera on the Chandra X-Ray Observatory. The X-ray period (P=0.13530915 s) is consistent with the extrapolation of the radio pulse period of PSR J1124-5916 for a spin-down rate of P{dot}=7.6x10^–13 s/s. The X-ray pulse is single-peaked and broad, with an FWHM width of 0.23P (83°). The pulse-averaged X-ray spectral properties of the pulsar are well described by a featureless power-law model with an absorbing column density N_H=3.1x10²¹ cm^–2, a photon index Γ=1.6, and an unabsorbed 0.3-10 keV band luminosity L_X=7.2x10³² ergs/s. We plausibly identify the location of the pulsar's termination shock. Pressure balance between the pulsar wind nebula and the larger synchrotron nebula, as well as lifetime issues for the X-ray-emitting electrons, argue for a particle-dominated pulsar wind nebula that is far from the minimum-energy condition. Upper limits on the surface temperature of the neutron star are at, or slightly below, values expected from ``standard'' cooling curves. There is no optical counterpart to the new pulsar; its optical luminosity is at least a factor of 5 below that of the Crab pulsar.