Discovery of an Energetic Pulsar Associated With SNR G76.9+1.0

We report the discovery of PSR J2022+3842, a 24 ms radio and X-ray pulsar in the supernova remnant G76.9+1.0, in observations with the Chandra X-ray Observatory , the Robert C. Byrd Green Bank Radio Telescope, and the Rossi X-ray Timing Explorer ( RXTE ). The pulsar's spin-down rate implies a rotation-powered luminosity erg s −1 , a surface dipole magnetic field strength B s = 1.0 × 10 12 G, and a characteristic age of 8.9 kyr. PSR J2022+3842 is thus the second-most energetic Galactic pulsar known, after the Crab pulsar, as well as the most rapidly rotating young, radio-bright pulsar known. The radio pulsations are highly dispersed and broadened by interstellar scattering, and we find that a large (δ f / f ≈ 1.9 × 10 −6 ) spin glitch must have occurred between our discovery and confirmation observations. The X-ray pulses are narrow (0.06 cycles FWHM) and visible up to 20 keV, consistent with magnetospheric emission from a rotation-powered pulsar. The Chandra X-ray image identifies the pulsar with a hard, unresolved source at the midpoint of the double-lobed radio morphology of G76.9+1.0 and embedded within faint, compact X-ray nebulosity. The spatial relationship of the X-ray and radio emissions is remarkably similar to the extended structure seen around the Vela pulsar. The combined Chandra and RXTE pulsar spectrum is well fitted by an absorbed power-law model with column density N H = (1.7 ± 0.3) × 10 22 cm −2 and photon index Γ = 1.0 ± 0.2; this implies that the Chandra point-source flux is virtually 100% pulsed. For a distance of 10 kpc, the X-ray luminosity of PSR J2022+3842 is L X (2–10 keV) = 7.0 × 10 33 erg s −1 . Despite being extraordinarily energetic, PSR J2022+3842 lacks a bright X-ray wind nebula and has an unusually low conversion efficiency of spin-down power to X-ray luminosity, .