PSR J0007+7303 IN THE CTA1 SUPERNOVA REMNANT: NEW GAMMA-RAY RESULTS FROM TWO YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS
- Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States)
- Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy)
- Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
- Praxis Inc., Alexandria, VA 22303 (United States)
One 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 two years of Large Area Telescope (LAT) survey data, we report on the discovery of {gamma}-ray emission in the off-pulse phase interval at the {approx}6{sigma} level. The emission appears to be extended at the {approx}2{sigma} level with a disk of extension {approx}0.{sup 0}6. level. The flux from this emission in the energy range E {>=} 100 MeV is F{sub 100} = (1.73 {+-} 0.40{sub stat} {+-} 0.18{sub sys}) Multiplication-Sign 10{sup -8} photons cm{sup -2} s{sup -1} and is best fitted by a power law with a photon index of {Gamma} = 2.54 {+-} 0.14{sub stat} {+-} 0.05{sub sys}. The pulsed {gamma}-ray flux in the same energy range is F{sub 100} = (3.95 {+-} 0.07{sub stat} {+-} 0.30{sub sys}) Multiplication-Sign 10{sup -7} photons cm{sup -2} s{sup -1} and is best fitted by an exponentially cutoff power-law spectrum with a photon index of {Gamma} = 1.41 {+-} 0.23{sub stat} {+-} 0.03{sub sys} and a cutoff energy E{sub c} = 4.04 {+-} 0.20{sub stat} {+-} 0.67{sub sys} GeV. We find no flux variability either at the 2009 May glitch or 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 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.
- OSTI ID:
- 22004200
- Journal Information:
- Astrophysical Journal, Vol. 744, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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