Discovery of Radio Pulsations from the X-Ray Pulsar J0205+6449 in Supernova Remnant 3C 58 with the Green Bank Telescope

We report the discovery with the 100 m Green Bank Telescope of 65 ms radio pulsations from the X-ray pulsar J02056449 at the center of supernova remnant 3C 58, making this possibly the youngest radio pulsar known. From our observations at frequencies of 820 and 1375 MHz, the free-electron column density to PSR J02056449 is found to be cm pc. The barycentric pulsar period P and period derivative 3 ˙ 140.7 0.3 P determined from a phase-coherent timing solution are consistent with the values previously measured from Xray observations. The averaged radio profile of PSR J0205 6449 consists of one sharp pulse of width ≈ 3m s ≈ 0.05P. The pulsar is an exceedingly weak radio source, with a pulse-averaged flux density in the 1400 MHz band of ∼45 mJy and a spectral index of ∼2.1. Its radio luminosity of ∼0.5 mJy kpc 2 at 1400 MHz is lower than that of ∼99% of known pulsars and is the lowest among known young pulsars. Subject headings: ISM: individual (3C 58) — pulsars: individual (PSR J02056449) — supernova remnants