Physics of magnetospheric emission in soft gamma-ray repeaters

Fulvio Melia, Marco Fatuzzo

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Soft gamma-ray repeaters appear to be relatively young, strongly magnetized neutron stars embedded within plerions. The observationally inferred presence of teragauss fields and energetic outflows in these sources provides some support for a model in which the bursts results from crustal disturbances that load and energize the magnetosphere with the ensuing generation of sheared Alfvén waves. We here determine accurately the structure of the particle efflux and calculate the spectrum of the resultant radiation, incorporating the key effects due to mildly relativistic magnetic bremsstrahlung, a frequency-dependent photospheric radius and angle-dependent boosting of the intensity for emitting elements at different inclinations. We find that the average photospheric radius during the transient event is ∼4 stellar radii and that the particles attain a Lorentz factor ∼13.2 by the time the gas becomes optically thin. The calculated spectrum is a weighted integral over the boosted intensity determined from the physical conditions (i.e., magnetic field, particle density, and temperature) at the photospheric radius corresponding to the relevant frequency. When applied to SGR 1806-20, this procedure yields a distance D ≈ 10 kpc to this source, which appears to be consistent with the range (∼8-17 kpc) inferred from its apparent coincidence with the supernova remnant G10.0-0.3.

Original languageEnglish (US)
Pages (from-to)904-907
Number of pages4
JournalAstrophysical Journal
Volume438
Issue number2
StatePublished - Jan 10 1995

Fingerprint

repeaters
physics
gamma rays
radii
efflux
magnetosphere
outflow
supernova remnants
energetics
magnetospheres
bremsstrahlung
neutron stars
magnetic field
inclination
disturbance
bursts
disturbances
gas
particle
radiation

Keywords

  • Acceleration of particles
  • Gamma rays: bursts
  • MHD
  • Pulsars: general
  • Stars: individual (SGR 0525-66)
  • Stars: neutron

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Physics of magnetospheric emission in soft gamma-ray repeaters. / Melia, Fulvio; Fatuzzo, Marco.

In: Astrophysical Journal, Vol. 438, No. 2, 10.01.1995, p. 904-907.

Research output: Contribution to journalArticle

Melia, Fulvio ; Fatuzzo, Marco. / Physics of magnetospheric emission in soft gamma-ray repeaters. In: Astrophysical Journal. 1995 ; Vol. 438, No. 2. pp. 904-907.
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