DEATH LINE OF GAMMA-RAY PULSARS WITH OUTER GAPS

Journal Article · Mon Aug 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/736/2/127· OSTI ID:21578240

Wang, Ren-Bo ^[1]; Hirotani, Kouichi ^[2]

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1. Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China)
2. Theoretical Institute for Advanced Research in Astrophysics (TIARA), Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei, Taiwan (China)

We analytically investigate the condition for a particle accelerator to be active in the outer magnetosphere of a rotation-powered pulsar. Within the accelerator (or the gap), the magnetic-field-aligned electric field accelerates electrons and positrons, which emit copious gamma-rays via the curvature process. If one of the gamma-rays emitted by a single pair materializes as a new pair on average, the gap is self-sustained. However, if the neutron-star spin-down rate decreases below a certain limit, the gap becomes no longer self-sustained and the gamma-ray emission ceases. We explicitly compute the multiplicity of cascading pairs and find that the obtained limit corresponds to a modification of the previously derived outer-gap death line. In addition to this traditional death line, we find another death line, which becomes important for millisecond pulsars, by separately considering the threshold of photon-photon pair production. Combining these traditional and new death lines, we give predictions on the detectability of gamma-ray pulsars with Fermi and AGILE. An implication for X-ray observations of heated polar-cap emission is also discussed.

• OSTI ID: 21578240
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 736; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BOSONS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
FERMIONS
GAMMA RADIATION
INTERACTIONS
IONIZING RADIATIONS
LEPTONS
MAGNETIC FIELDS
MASSLESS PARTICLES
MATTER
NEUTRON STARS
PAIR PRODUCTION
PARTICLE PRODUCTION
PHOTONS
POSITRONS
PULSARS
RADIATIONS
STARS