ISSN:
1572-946X
Keywords:
Soft Gamma Repeaters
;
neutron stars
;
magnetic fields
;
gamma-rays
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The exotic quantum process of photon splittingϒ →ϒϒ has great potential to explain the softness of emission in soft gamma repeaters (SGRs) if they originate in neutron stars with surface fields above the quantum critical fieldB cr = 4.413×1013 Gauss. Splitting becomes prolific at such field strengths: its principal effect is to degrade photon energies, initiating a cascade that softens gamma-ray spectra. Uniform field cascade calculations have demonstrated that emission could be softened to the observed SGR energies for fields exceeding about 1014 Gauss. Recently, we have determined splitting attenuation lengths and maximum energies for photon escape in neutron star environments including the effects of magnetospheric dipole field geometry. Such escape energies εesc suitably approximate the peak energy of the emergent spectrum, and in this paper we present results forε esc as a function of photon emission angles for polar cap and equatorial emission regions. The escape energy is extremely insensitive to viewing perspective for equatorial emission, arguing in favour of such a site for the origin of SGR activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00658591
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