The spectral and beaming characteristics of the anomalous X-ray pulsar 4U 0142 61 - Astrophysics > High Energy Astrophysical PhenomenaReportar como inadecuado




The spectral and beaming characteristics of the anomalous X-ray pulsar 4U 0142 61 - Astrophysics > High Energy Astrophysical Phenomena - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: AXPs and SGRs constitute a special population of young neutron stars, whichare thought to be magnetars, i.e., neutron stars with super-strong magneticfields 10^14 - 10^15 G. Assuming that AXPs and SGRs accrete matter from afallback disk, we attempt to explain the energy-dependent pulse profiles of AXP4U 0142+61, as well as its phase-dependent energy spectra. In the fallback diskmodel, the Thomson optical depth along the accretion funnel is significant andbulk-motion Comptonization operates efficiently. This is enhanced by resonantcyclotron scattering. The thus scattered photons escape mainly sideways andproduce a fan beam, which is detected as a main pulse up to energies of ~160keV. The approximately isotropic emission from the stellar surface softthermal photons and reflected hard X-ray ones is detected as a secondarypulse. This secondary pulse shows a bump at an energy of ~60 keV, which may beinterpreted as resonant cyclotron scattering of fan-beam photons at theneutron-star surface, implying a dipole magnetic field strength B ~7 x 10^121+z G, where z is the gravitational redshift. Our model explains the soft andhard X-ray spectra of 4U 0142+61 and its energy dependent pulse profiles of thequiescent emission, while the short bursts are due to magnetar-type processestaking place in superstrong multiple fields.



Autor: J. E. Trümper, N. D. Kylafis, Ü. Ertan, A. Zezas

Fuente: https://arxiv.org/



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