Neutron Star Kicks in Isolated and Binary Pulsars: Observational Constraints and Implications for Kick Mechanisms
Neutron Star Kicks in Isolated and Binary Pulsars: Observational Constraints and Implications for Kick Mechanisms
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DOI：
10.1086/499397
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发表时间：
2005-09
期刊：
影响因子：
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通讯作者：
Chen Wang;D. Lai;J. Han
中科院分区：
文献类型：
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作者：
Chen Wang;D. Lai;J. Han
我们研究了孤立脉冲星和双星系统中子星（NS）的观测约束。我们特别感兴趣的是自旋方向/错位的证据及其对NS初始自旋周期的依赖。对于一些年轻的脉冲星，对致密星云的x射线观测表明，脉冲星的固有运动与星云对称轴定义的自旋方向一致。我们也严格检查测量的固有运动和投影自转轴从脉冲星的大样本校准良好的极化数据。我们发现，在24颗脉冲星中，有可靠的测量，在自转轴和固有运动之间有显著的相关性。对于各种NS双星系统，包括双NS系统、具有大质量主序星伴星的双星系统和具有大质量白矮星伴星的双星系统，我们从观测到的系统轨道特征中获得了对踢星等和方向的约束。我们发现，在许多系统中，踢球速度与NS自旋轴不一致，并且这些系统中的NS自旋周期（当可用时）通常长于数百毫秒。这些约束，加上在许多孤立脉冲星中观测到的自旋-踢准，表明踢准的时间尺度在数百毫秒到1秒之间，因此可以根据NS的初始自旋周期来获得自旋-踢准或不对准。我们讨论了我们的结果对各种nskick机制的含义。
We study observational constraints on neutron star (NS) kicks for isolated pulsars and for NSs in binary systems. We are particularly interested in the evidence of kick-spin alignment/misalignment and its dependence on the NS initial spin period. For several young pulsars, X-ray observations of compact nebulae showed that pulsar proper motion is aligned with the spin direction as defined by the symmetry axis of the nebula. We also critically examine the measurements of the proper motion and the projected spin axis from a large sample of pulsars with well-calibrated polarization data. We find that among the two dozen pulsars for which reliable measurements are available, there is a significant correlation between the spin axis and the proper motion. For various NS binaries, including double NS systems, binaries with massive main-sequence star companions, and binaries with massive white-dwarf companions, we obtain constraints on the kick magnitudes and directions from the observed orbital characteristics of the system. We find that the kick velocity is misaligned with the NS spin axis in a number of systems, and the NS spin period (when available) in these systems is generally longer than several hundred milliseconds. These constraints, together with the spin-kick alignment observed in many isolated pulsars, suggest that the kick timescale is hundreds of milliseconds to 1 s, so that spin-kick alignment or misalignment can be obtained depending on the initial spin period of the NS. We discuss the implication of our result for various NS kick mechanisms.