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We discuss growing evidence that pulsar high energy is emission is generated via Inverse Compton mechanism. We reproduce the broadband spectrum of Crab pulsar, from UV to very high energy gamma-rays - nearly ten decades in energy, within the framework of the cyclotron-self-Compton model. Emission is produced by two counter-streaming beams within the outer gaps, at distances above ∼ 20 NS radii. The outward moving beam produces UV-X-ray photons via Doppler-booster cyclotron emission, and GeV photons by Compton scattering the cyclotron photons produced by the inward going beam. The scattering occurs in the deep Klein-Nishina regime, whereby the IC component provides a direct measurement of particle distribution within the magnetosphere. The required plasma multiplicity is high, ∼ 106-107, but is consistent with the average particle flux injected into the pulsar wind nebula. [ABSTRACT FROM AUTHOR]

The electromagnetic model assumes that rotational energy of a relativistic, stellar-mass central source (black-hole-accretion disk system or fast rotating neutron star) is converted into magnetic energy through unipolar dynamo mechanism, propagated to large distances in a form of relativistic, subsonic, Poynting flux-dominated wind and is dissipated directly into emitting particles through current-driven instabilities. Collimating effects of magnetic hoop stresses lead to strongly non-spherical expansion and formation of jets. Long and short GRBs may develop in a qualitatively similar way, except that in case of long burst ejecta expansion has a relatively short, non-relativistic, strongly dissipative stage inside the star. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Poynting flux driven outflows from magnetized rotators are a plausible explanation for gamma-ray burst engines. We suggest a new possibility for how such outflows might transfer energy into radiating particles. We argue that in region near the rotation axis the Poynting flux drives non-linearly unstable large amplitude electromagnetic waves (LAEMW) which "break" at radii ϒ[SUBt] ∼ 10[SUP14] cm where the MHD approximation becomes inapplicable. In the "foaming" (relativistically reconnecting) regions formed during the wave breaks the random electric fields stochastically accelerate particles to ultrarelativistic energies which then radiate in turbulent electromagnetic fields. The typical energy of the emitted photons is a fraction of the fundamental Compton energy ε ∼ ƒhc/ϒ[SUBe] with ƒ ∼ 10[SUP-3] plus additional boosting due to the bulk motion of the medium. The emission properties are similar to synchrotron radiation, with a typical cooling time ∼ 10[SUP-3] sec. During the wave break, the plasma is also bulk accelerated in the outward radial direction and at larger radii can produce afterglows due to the interactions with external medium. The near equipartition fields required by afterglow models may be due to magnetic field regeneration in the outflowing plasma (similarly to the field generation by LAEMW of laser-plasma interactions) and mixing with the upstream plasma. [ABSTRACT FROM AUTHOR]