Gamma-ray bursts from Sheared Alfvén waves

Fulvio Melia, Marco Fatuzzo

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Sheared Alfvén waves in strongly magnetized neutron stars are efficient particle accelerators by virtue of the large electric field components Ez they generate parallel to the unperturbed magnetic field B0 = B0 ẑ. For example, with an amplitude BA0 = 1011 G (=0.1B0) and a shear wavenumber m = 0.5 (corresponding to a crustal perturbation length scale of ≈10 cm), these waves can accelerate electrons to a Lorentz factor y ∼ 104-5 within 5 km of the stellar surface, even under the influence of a Compton drag due to the thermal emission of a warm (Tpc ≲ 1 keV) polar cap. Here, we apply this physical process to a study of gamma-ray bursts, taking into account both resonant and nonresonant scattering. We also discuss several very encouraging features of the model. (1) Although the field is oscillatory, virtually all the charges are ejected from the system, resulting in very little backheating of the stellar surface. (2) The particle number density (and hence the burst energy) is accounted for naturally in terms of BA0 and m, which in principle are known from the physical manifestation of the agent causing the crustal disturbance (e.g., a thermonuclear explosion or a starquake). (3) The resulting y-ray spectrum compares very favorably with the observations. And (4) this model restricts the geometry of the emission region, in the sense that only the Compton upscattering of soft photons from a warm polar cap (as opposed, e.g., to an isotropic source) will produce the correct spectral shape.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume383
Issue number2 PART 2
StatePublished - Dec 20 1991

Fingerprint

polar caps
gamma ray bursts
thermonuclear explosions
particle accelerators
thermal emission
neutron stars
drag
electric field
explosion
bursts
rays
disturbances
scattering
perturbation
shear
magnetic field
disturbance
geometry
electron
electric fields

Keywords

  • Gamma rays: bursts
  • Gamma rays: general
  • Magnetic fields
  • Particle acceleration
  • Pulsars
  • Quantum mechanics

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Gamma-ray bursts from Sheared Alfvén waves. / Melia, Fulvio; Fatuzzo, Marco.

In: Astrophysical Journal, Vol. 383, No. 2 PART 2, 20.12.1991.

Research output: Contribution to journalArticle

Melia, F & Fatuzzo, M 1991, 'Gamma-ray bursts from Sheared Alfvén waves', Astrophysical Journal, vol. 383, no. 2 PART 2.
Melia, Fulvio ; Fatuzzo, Marco. / Gamma-ray bursts from Sheared Alfvén waves. In: Astrophysical Journal. 1991 ; Vol. 383, No. 2 PART 2.
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