THE VERY HIGH ENERGY EMISSION FROM PULSARS: A CASE FOR INVERSE COMPTON SCATTERING

Journal Article · Fri Jul 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/754/1/33· OSTI ID:22039302

Lyutikov, Maxim ^[1]; Otte, Nepomuk ^[2]; McCann, Andrew ^[3]

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1. Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States)
2. Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95060 (United States)
3. Department of Physics, McGill University, Montreal, QC, H3A 2T8 (Canada)

The observations of gamma-ray emission from pulsars with the Fermi-LAT detector and the detection of the Crab pulsar with the VERITAS array of Cherenkov telescopes at energies above 100 GeV make it unlikely that curvature radiation is the main source of photons above GeV energies in the Crab and many other pulsars. We outline a model in which the broad UV-X-ray component and the very high energy {gamma}-ray emission of pulsars are explained within the synchrotron self-Compton framework. We argue that the bulk of the observed radiation is generated by the secondary plasma, which is produced in cascades in the outer gaps of the magnetosphere. We find that the inverse Compton (IC) scattering occurs in the Klein-Nishina regime, which favors synchrotron photons in the UV band as target field for the scattering process. The primary beam is accelerated in a modest electric field, with a field strength that is of the order of a few percent of the magnetic field near the light cylinder. Overall, for IC scattering occurring in the Klein-Nishina regime, the particle distribution in the gap does not evolve toward a stationary distribution and thus is intrinsically time-dependent. We point out that in a radiation reaction-limited regime of particle acceleration the gamma-ray luminosity L{sub {gamma}} scales linearly with the pulsar spin-down power E-dot , L{sub {gamma}}{proportional_to} E-dot , and not proportional to {radical}( E-dot ) as expected from potential-limited acceleration.

• OSTI ID: 22039302
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 754; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
ASTROPHYSICS
COMPTON EFFECT
CRAB NEBULA
ELECTRIC FIELDS
GAMMA ASTRONOMY
GAMMA RADIATION
GEV RANGE
LUMINOSITY
MAGNETIC FIELDS
PHOTON EMISSION
PLASMA
PULSARS
SPIN
STARS
TIME DEPENDENCE
VISIBLE RADIATION
X RADIATION