2012ApJ...744..146A

One of the main results of the Fermi Gamma-Ray Space Telescope is the discovery of γ-ray selected pulsars. The high magnetic field pulsar, PSR J0007+7303 in CTA1, was the first ever to be discovered through its γ-ray pulsations. Based on analysis of two years of Large Area Telescope (LAT) survey data, we report on the discovery of γ-ray emission in the off-pulse phase interval at the ∼6σ level. The emission appears to be extended at the ∼2σ level with a disk of extension ∼0°.6. level. The flux from this emission in the energy range E ≥ 100 MeV is F₁₀₀= (1.73 ±0.40_stat± 0.18_sys)x10^–8 photons/cm2/s and is best fitted by a power law with a photon index of Γ = 2.54±0.14_stat± 0.05_sys. The pulsed γ-ray flux in the same energy range is F₁₀₀= (3.95 ± 0.07_stat± 0.30_sys)x10^–7 photons/cm2/s and is best fitted by an exponentially cutoff power-law spectrum with a photon index of Γ = 1.41±0.23_stat± 0.03_sys and a cutoff energy E_c= 4.04±0.20_stat ±0.67_sysGeV. We find no flux variability either at the 2009 May glitch or in the long-term behavior. We model the γ-ray light curve with two high-altitude emission models, the outer gap and slot gap, and find that the preferred model depends strongly on the assumed origin of the off-pulse emission. Both models favor a large angle between the magnetic axis and observer line of sight, consistent with the nondetection of radio emission being a geometrical effect. Finally, we discuss how the LAT results bear on the understanding of the cooling of this neutron star.