We consider the voltage structure in the open-field circuit and outer magnetosphere of a magnetar. The standard polar-cap model for radio pulsars is modified significantly when the polar magnetic field exceeds 1.8x10^{14} G. Pairs are created by accelerated particles via resonant scattering of thermal X-rays, followed by the nearly instantaneous conversion of the scattered photon to a pair. A surface gap is then efficiently screened by e+- creation, which regulates the voltage in the inner part of the circuit to ~10^9 V. We also examine the electrostatic gap structure that can form when the magnetic field is somewhat weaker, and deduce a voltage 10-30 times larger over a range of surface temperatures. We examine carefully how the flow of charge back to the star above the gap depends on the magnitude of the current that is extracted from the surface of the star, on the curvature of the magnetic field lines, and on resonant drag. The rates of different channels of pair creation are determined self-consistently, including the non-resonant scattering of X-rays, and collisions between gamma rays and X-rays. We find that the electrostatic gap solution has too small a voltage to sustain the observed pulsed radio output of magnetars unless i) the magnetic axis is nearly aligned with the rotation axis and the light of sight; or ii) the gap is present on the closed as well as the open magnetic field lines. Several properties of the radio magnetars -- their rapid variability, broad pulses, and unusually hard radio spectra -- are consistent with a third possibility, that the current in the outer magnetosphere is strongly variable, and a very high rate of pair creation is sustained by a turbulent cascade.
Changes in the X-ray Emission from the Magnetar Candidate 1E 2259+586 during its 2002 Outburst
2002年6月，从异常X射线脉冲星（AXP）1 E 2259+586上探测到了80多个单独的爆发，类似于从软伽马中继站（SGR）上看到的爆发。与此爆发活动相一致的是脉冲通量、持续通量、能谱、脉冲轮廓和潜在X射线源的自旋下降的总体变化。我们目前的RXTE和XMM-牛顿观测1 E 2259+586，显示上述源参数的演变过程中和之后的这一插曲。具体来说，我们观察到X射线通量增加了一个数量级以上，具有两个不同的组件。第一个成分与爆发活动有关，在~2天内衰减，在此期间，能量谱比源的静止状态要硬得多。第二分量在毛刺之后的一年中根据指数为-0.22 +/-0.01的幂律时间衰减。脉冲分数最初下降到~ 15%RMS，并且脉冲轮廓在爆发期间显著改变。在观察到的爆发活动之前，在1 E 2259+586中观察到一个毛刺。一小部分毛刺（~19%）恢复，尽管恢复不是纯粹的指数。在时间尺度为~14天的情况下，频率跳变的~20%的指数上升导致与数据的显著更好的拟合，然而，不能排除来自脉冲轮廓相位中的系统漂移的污染。长期的故障后降速率相对于故障前的值在幅度上有所下降。与SGR的爆发性能，物理解释的结果，并在我们的银河系中的候选磁星的数量的影响进行了比较讨论。
The Compact X-ray Source 1E 1547.0-5408 and the Radio Shell G327.24-0.13: A New Proposed Association between a Candidate Magnetar and a Candidate Supernova Remnant
本文介绍了银道面上以X射线源1 E 1547.0-5408为中心的场的X射线、红外和射电观测。一个新的钱德拉观察这个源表明，它是无法解决的弧秒分辨率，和一个新的XMM观察表明，它的X射线光谱是最好的描述吸收幂律和黑体模型。对1980年至2006年期间从该源观测到的X射线通量的比较表明，在此期间，其吸收的0.5-10 keV X射线通量从约2 x10 ^-12 ergs cm-2 s-1下降到约3 x10 ^-13 ergs cm-2。最新的XMM观测结果使我们能够将0.5-10 keV峰-峰脉冲部分的5 sigma置信上限定为14%。对这个场的近红外观测显示，在1 E 1547.0-5408的位置附近有一个星等Ks = 15.9+/-0.2的源，但隐含的X射线与红外通量比表明红外辐射来自一个不相关的场源，使我们能够将1 E 1547.0-5408的IR星等限制在>17.5。射电观测档案显示，1 E 1547.0-5408位于一个微弱的小射电壳G327.24-0.13（直径4'）的中心，这可能是一个以前未被确认的超新星遗迹。1 E 1547.0-5408的X射线特性表明，这个源是一颗磁星--一颗年轻的中子星，其X射线发射是由其极强的磁场的衰变提供动力的。这个源和G327.24-0.13之间的空间重合表明1 E 1547.0-5408与一个年轻的超新星遗迹有关，支持中子星的解释。需要额…
