Relativistic Effects and Polarization in Three High-Energy Pulsar Models
Relativistic Effects and Polarization in Three High-Energy Pulsar Models
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DOI：
10.1086/383121
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发表时间：
2004-01
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影响因子：
--
通讯作者：
J. Dyks;A. Harding;B. Rudak
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文献类型：
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作者：
J. Dyks;A. Harding;B. Rudak
讨论了像差和光程延迟的特殊相对论效应对脉冲星高能光曲线和偏振特性的影响，并用三种模型预测了它们的偏振特性：两极焦散模型、外间隙模型和极帽模型。计算了模型的位置、角度曲线和偏振度，并与Crab脉冲星的光学数据进行了比较。详细讨论了模型中伽马射线和射电光曲线中峰值的相对位置。我们发现，双极焦散模型可以定性地再现Crab脉冲星的光学偏振特性：位置角的快速摆动和偏振度的极小值，与两个峰值相关。观测到的通量和偏振度之间的反相关关系(在光学波段也观察到B0656+14)自然是由于模型中的峰的焦散性质造成的，这些峰是由于来自不同高度的辐射的叠加而产生的，即在不同的角度上极化。两极焦散模型也提供了一个可接受的解释蟹的无线电剖面的主要特征。外隙模型和极帽模型都不能再现CRAB上的光偏振数据。虽然外隙模型非常成功地再现了伽马射线和射电峰值在脉冲分布中的相对位置，但它只有在计入离光柱非常近的区域的光子发射时才能再现高能光曲线。
We present the influence of the special relativistic effects of aberration and light-travel time delay on pulsar high-energy light curves and polarization characteristics predicted by three models: the two-pole caustic model, the outer gap model, and the polar cap model. Position angle curves and degree of polarization are calculated for the models and compared with the optical data on the Crab pulsar. The relative positions of peaks in gamma-ray and radio light curves are discussed in detail for the models. We find that the two-pole caustic model can qualitatively reproduce the optical polarization characteristics of the Crab pulsar: fast swings of the position angle and minima in polarization degree, associated with both peaks. The anticorrelation between the observed flux and the polarization degree (observed in the optical band also for B0656+14) naturally results from the caustic nature of the peaks, which are produced in the model because of the superposition of radiation from many different altitudes, i.e., polarized at different angles. The two-pole caustic model also provides an acceptable interpretation of the main features in the Crab's radio profile. Neither the outer gap model nor the polar cap model is able to reproduce the optical polarization data on the Crab. Although the outer gap model is very successful in reproducing the relative positions of gamma-ray and radio peaks in pulse profiles, it can reproduce the high-energy light curves only when photon emission from regions very close to the light cylinder is included.