Program

Resonant Cyclotron Scattering and Comptonization in Neutron Star Magnetospheres

Maxim Lyutikov

UBC

Abstract:

Resonant cyclotron scattering of the surface radiation in magnetospheres of neutron stars may considerably modify emergent spectra. Resonant tranfer has a number of unusual characteristics: (i) in the limit of high resonant optical depth, cyclotron resonant layer is half opaque, in a sharp contrast to the case of non-resonant scattering; (ii) transmitted flux is on average Compton up-scattered by 1+ 2 betaT, where betaT is a typical thermal velocity in units of the velocity of light; reflected flux has on average the initial frequency. (iii) for both transmitted and reflected fluxes the dispersion of intensity decreases with increasing optical depth; (iv) emerging spectrum is appreciably non-Plankian while narrow spectral features produced at the surface are erased; (v) optical optical photons are less affected by resonant Comptonization than X-rays due to different polarization of normal modes in resonances. We discuss applications to Anomaous X-ray Pulsars and thermally emitting Isolated Neutron Stars

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