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PSR J0007+7303 in the CTA1 SNR: New Gamma-ray Results from Two Years of Fermi-LAT ObservationsOne of the main results of the Fermi Gamma-Ray Space Telescope is the discovery of gamma-ray selected pulsars. The high magnetic field pulsar, PSR J0007+7303 in CTA1, was the first ever to be discovered through its gamma-ray pulsations. Based on analysis of 2 years of LAT survey data, we report on the discovery of I-ray emission in the off-pulse phase interval at the approx. 6sigma level. The flux from this emission in the energy range E > or =::: 100 MeV is F(sub 100) = (1.73+/-0.40) x 10(exp -8) photons/sq cm/s and is best fitted by a power law with a photon index of Gamma = 2.54+/-0.14. The pulsed gamma-ray flux in the same energy range is F(sub 100) = (3.95+/-0.07) x 10(exp -7) photons/sq cm/s and is best fitted by an exponentially-cutoff power-law spectrum with a photon index of Gamma = 1.41+/-0.23 and a cutoff energy E(sub c) = 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 gamma-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.
Document ID
20120008053
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Abdo, A. A.
(George Mason Univ. Fairfax, VA, United States)
Wood, K. S.
(Naval Research Lab. Washington, DC, United States)
DeCesar, M. E.
(Maryland Univ. College Park, MD, United States)
Gargano, F.
(Istituto Nazionale di Fisica Nucleare Bari, Italy)
Giordano, F.
(Istituto Nazionale di Fisica Nucleare Bari, Italy)
Ray, P. S.
(Naval Research Lab. Washington, DC, United States)
Parent, D.
(George Mason Univ. Fairfax, VA, United States)
Harding, A. K.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Miller, M. Coleman
(Maryland Univ. College Park, MD, United States)
Wood, D. L.
(Praxis, Inc. Alexandria, VA, United States)
Wolff, M. T.
(Naval Research Lab. Washington, DC, United States)
Date Acquired
August 25, 2013
Publication Date
July 21, 2011
Subject Category
Astronomy
Report/Patent Number
GSFC.ABS.5880.2012
Distribution Limits
Public
Copyright
Public Use Permitted.
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