Heartbeat of the Mouse: A Young Radio Pulsar Associated with the Axisymmetric Nebula G359.23−0.82

We report the discovery of PSR J1747-2958, a radio pulsar with period P = 98 ms and dispersion measure DM = 101 cm -3 pc, in a deep observation with the Parkes telescope of the axially symmetric "Mouse" radio nebula (G359.23-0.82). Timing measurements of the newly discovered pulsar reveal a characteristic age P /2 = 25 kyr and spin-down luminosity = 2.5 × 10 36 ergs s -1 . The pulsar (timing) position is consistent with that of the Mouse's "head." The distance derived from the DM (≈2 kpc) is consistent with the Mouse's distance limit from H I absorption (<5.5 kpc). Also, the X-ray energetics of the Mouse are compatible with being powered by the pulsar. Therefore, we argue that PSR J1747-2958, moving at supersonic speed through the local interstellar medium, powers this unusual nonthermal nebula. The pulsar is a weak radio source, with a period-averaged flux density at 1374 MHz of 0.25 mJy and a luminosity of ~1 mJy kpc 2 .