PSR J0007+7303 In The CTA1 Supernova Remnant: New Gamma-Ray Results From Two Years Of Fermi Large Area Telescope Observations
- George Mason Univ., Fairfax, VA (United States); Naval Research Lab. (NRL), Washington, DC (United States)
- Naval Research Lab. (NRL), Washington, DC (United States)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
- Istituto Nazionale di Fisica Nucleare (INFN), Bari (Italy)
- Istituto Nazionale di Fisica Nucleare (INFN), Bari (Italy); Univ. e del Politecnico di Bari (Italy)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
- Univ. of Maryland, College Park, MD (United States)
- Praxis Inc., Alexandria, VA (United States); Naval Research Lab. (NRL), Washington, DC (United States)
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 2 years of LAT survey data, we report on the discovery of γ-ray emission in the off-pulse phase interval at the ~ 6σ level. The flux from this emission in the energy range E ≥ 100 MeV is F100 = (1.73±0.40)×10-8 photons cm-2 s-1 and is best fitted by a power law with a photon index of Γ = 2.54±0.14. The pulsed -ray flux in the same energy range is F100 = (3.95±0.07)×10-7 photons cm-2 s-1 and is best fitted by an exponentially-cutoff power-law spectrum with a photon index of Γ = 1.41 ± 0.23 and a cutoff energy Ec = 4.04 ± 0.20 GeV. We find no flux variability neither at the 2009 May glitch nor 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 model that best fits the data 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.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1356766
- Journal Information:
- The Astrophysical Journal, Vol. 744, Issue 2; ISSN 0004-637X
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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