Pulsed Gamma Rays from the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP to be detected in gamma rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma-Ray Observatory. The spin-down power dot{E} = 3.5 10^{33} erg s<SUP>-1</SUP> is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, 0.07 0.01 and 0.08 0.02 wide, respectively, separated by 0.44 0.02 in phase. The first gamma-ray peak falls 0.15 0.01 after the main radio peak. The pulse shape is similar to that of the "normal" gamma-ray pulsars. An exponentially cutoff power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 1.05 1.35) 10<SUP>-8</SUP> cm<SUP>-2</SUP> s<SUP>-1</SUP> with cutoff energy (1.7 0.4 0.5) GeV. Based on its parallax distance of (300 90) pc, we obtain a gamma-ray efficiency L_gamma/ dot{E} ~= 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.