Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray Pulsars
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In this paper, the authors considered the structure of neutron star magnetospheres threaded by large-scale electrical currents and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra and pulse profiles.Abstract:
(ABBREVIATED) We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents, and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra and pulse profiles. In the magnetar model for the SGRs and AXPs, these currents are maintained by magnetic stresses acting deep inside the star. We construct self-similar, force-free equilibria of the current-carrying magnetosphere with a power-law dependence of magnetic field on radius, B ~ r^(-2-p), and show that a large-scale twist softens the radial dependence to p < 1. The spindown torque acting on the star is thereby increased in comparison with a vacuum dipole. We comment on the strength of the surface magnetic field in the SGR and AXP sources, and the implications of this model for the narrow measured distribution of spin periods. A magnetosphere with a strong twist, B_\phi/B_\theta = O(1) at the equator, has an optical depth ~ 1 to resonant cyclotron scattering, independent of frequency (radius), surface magnetic field strength, or charge/mass ratio of the scattering charge. When electrons and ions supply the current, the stellar surface is also heated by the impacting charges at a rate comparable to the observed X-ray output of the SGR and AXP sources, if B_{dipole} ~ 10^{14} G. Redistribution of the emerging X-ray flux at the ion and electron cyclotron resonances will significantly modify the emerging pulse profile and, through the Doppler effect, generate a non-thermal tail to the X-ray spectrum. The sudden change in the pulse profile of SGR 1900+14 after the 27 August 1998 giant flare is related to an enhanced optical depth to electron cyclotron scattering, resulting from a sudden twist imparted to the external magnetic field.read more
Citations
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Journal ArticleDOI
Untwisting magnetospheres of neutron stars
TL;DR: In this paper, the authors derived an equation describing the evolution of the magnetosphere of neutron stars and derived its solutions, and its solutions are presented. And they also discussed implications for other magnetars.
Journal ArticleDOI
Magnetar-like emission from the young pulsar in Kes 75.
Fotis P. Gavriil,Fotis P. Gavriil,M. E. Gonzalez,Eric V. Gotthelf,Victoria M. Kaspi,Margaret A. Livingstone,P. M. Woods +6 more
TL;DR: In this article, the authors reported the detection of magnetar-like x-ray bursts from the young pulsar PSR J1846-0258, at the center of the supernova remnant Kes 75.
Journal ArticleDOI
A Major Soft Gamma Repeater-like Outburst and Rotation Glitch in the No-longer-so-anomalous X-Ray Pulsar 1E 2259+586
Victoria M. Kaspi,Victoria M. Kaspi,Fotis P. Gavriil,P. M. Woods,Joseph B. Jensen,Mallory S. E. Roberts,Mallory S. E. Roberts,Deepto Chakrabarty +7 more
TL;DR: A major outburst from the anomalous X-ray pulsar 1E 2259+586 was reported in this article, in which over 80 Xray bursts were detected in 4 hours using the Rossi X-Ray Timing Explorer.
Journal ArticleDOI
NuSTAR DISCOVERY OF A 3.76 s TRANSIENT MAGNETAR NEAR SAGITTARIUS A
Kaya Mori,Eric V. Gotthelf,Shuo Zhang,Hongjun An,Frederick K. Baganoff,Nicolas M. Barrière,Andrei M. Beloborodov,Steven E. Boggs,Finn Erland Christensen,William W. Craig,Francois Dufour,Brian W. Grefenstette,Charles J. Hailey,Fiona A. Harrison,Jaesub Hong,Victoria M. Kaspi,J. A. Kennea,Kristin K. Madsen,Craig B. Markwardt,Melania Nynka,Daniel Stern,John A. Tomsick,William W. Zhang +22 more
TL;DR: In this article, the authors reported the discovery of 3.76 s pulsations from a new burst source near Sgr A^* observed by the NuSTAR observatory, which is known as SGR J1745-29.
Journal ArticleDOI
Explosive reconnection in magnetars
TL;DR: In this paper, the authors investigated the possibility that X-ray flares and bursts observed from anomalous x-ray pulsars and soft γ-ray repeaters result from magnetospheric reconnection events initiated by the development of the tearing mode in magnetically dominated relativistic plasma.
References
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