2006ApJ...637..456C

We have discovered the pulsar associated with the supernova remnant G21.5-0.9. PSR J1833-1034, with spin period P=61.8 ms and dispersion measure 169/cm3 pc, is very faint, with pulse-averaged flux density of ~70 µJy at a frequency of 1.4 GHz, and was first detected in a deep search with the Parkes telescope. Subsequent observations with Parkes and the Green Bank Telescope have confirmed this detection and yield a period derivative P{dot}=2.02x10^–13. These spin parameters imply a characteristic age τ_c=4.8 kyr and a spin-down luminosity E{dot}=3.3x10³⁷ ergs/s, the latter value exceeded only by the Crab pulsar among the rotation-powered pulsars known in our Galaxy. The pulsar has an unusually steep radio spectrum in the 0.8-2.0 GHz range, with power-law index ~3.0, and a narrow single-peaked pulse profile with FWHM of 0.04P. We have analyzed 350 ks of archival Chandra X-Ray Observatory HRC data and find a pointlike source of luminosity ~3x10^–5E{dot}, offset from the center of an elliptical region of size ~7''x5'' and luminosity ~10^–3E{dot} within which likely lies the pulsar wind termination shock. We have searched for X-ray pulsations in a 30 ks HRC observation without success, deriving a pulsed fraction upper limit for a sinusoidal pulse shape of about 70% of the pulsar flux. We revisit the distance to G21.5-0.9 based on H I and CO observations, arguing that it is 4.7±0.4 kpc. We use existing X-ray and radio observations of the pulsar wind nebula, along with the measured properties of its engine and a recent detection of the supernova remnant shell, to argue that G21.5-0.9 and PSR J1833-1034 are much younger than τ_cand likely their true age is ≲1000 yr. In that case, the initial spin period of the pulsar was ≳55 ms.