Résumé
We report the discovery of 31.18 ms pulsations from the INTEGRAL source IGR J14003-6326 using the Rossi X-ray Timing Explorer (RXTE). This pulsar is most likely associated with the bright Chandra X-ray point source lying at the center of G310.6-1.6, a previously unrecognized Galactic composite supernova remnant (SNR) with a bright central non-thermal radio and X-ray nebula, taken to be the pulsar wind nebula (PWN). PSR J1400-6325 is amongst the most energetic rotation-powered pulsars in the Galaxy, with a spin-down luminosity of \dot{E} = 5.1 × 10^{37} erg s-1. In the rotating dipole model, the surface dipole magnetic field strength is Bs = 1.1 × 1012 G and the characteristic age τ_c ≡ P/2\dot{P} = 12.7 kyr. The high spin-down power is consistent with the hard spectral indices of the pulsar and the nebula of 1.22 ± 0.15 and 1.83 ± 0.08, respectively, and a 2-10 keV flux ratio F PWN/F PSR ~ 8. Follow-up Parkes observations resulted in the detection of radio emission at 10 and 20 cm from PSR J1400-6325 at a dispersion measure of ~560 cm-3 pc, which implies a relatively large distance of 10 ± 3 kpc. However, the resulting location off the Galactic plane of ~280 pc would be much larger than the typical thickness of the molecular disk, and we argue that G310.6-1.6 lies at a distance of ~7 kpc. There is no gamma-ray counterpart to the nebula or pulsar in the Fermi data published so far. A multi-wavelength study of this new composite SNR, from radio to very high-energy gamma rays, suggests a young (lsim103 yr) system formed by a sub-energetic (lsim1050 erg), low ejecta mass (M ej ~ 3 M sun) supernova explosion that occurred in a low-density environment (n 0~ 0.01 cm-3).