Observations of PSR J2021+3651 and its X-ray pulsar wind nebula G75.2+0.1

We present the results from X-ray and radio observations of the recently discovered young Vela-like pulsar PSR J2021+3651, which is coincident with the EGRET gamma-ray source GeV 2020+3658. A 19.0 ks Chandra ACIS-S observation has revealed a similar to20"x10" pulsar wind nebula that is reminiscent of the equatorial tori seen around some young pulsars, along with thermal emission from an embedded point source (kT(infinity)=0.15+/-0.02 keV). We have named the nebula G75.2+0.1. Its spectrum is well fitted by an absorbed power-law model with a photon index of Gamma=1.7(-0.2)(+0.3), a hydrogen column density of N-H=(7.8(-1.4)(+1.7))x10(21) cm(-2), and an unabsorbed 0.5-10.0 keV flux of (1.7+/-0.1)x10(-12) ergs cm(-2) s(-1). We have spatially fitted G75.2+0.1 with a model that assumes a toroidal morphology, and from this we infer that the axis of the torus is highly inclined to the line of sight. A 20.8 ks Chandra observation in continuous-clocking mode reveals a possible pulse detection, with a pulsed fraction of similar to65% and an H-test probability of occurring by chance of 8.9x10(-5). Timing observations with the Arecibo radio telescope spanning 2 yr show that PSR J2021+3651 glitched sometime between MJD 52,616 and 52,645 with parameters Deltanu/nu=(2.587+/-0.002)x10(-6) and Delta(nu)over dot/(nu)over dot=(6.2+/-0.3)x10(-3), similar to those of the largest glitches observed in the Vela pulsar. PSR J2021+3651 is heavily scattered (tau(sc)=17.7+/-0.9 ms at 1 GHz) and exhibits a significant amount of timing noise.