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arXiv 0911.0502astro-ph.HE
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脉冲星磁排列和脉冲宽度-年龄关系

Pulsar magnetic alignment and the pulsewidth-age relation

Matthew D. T. Young, Lee S. Chan, Ron R. Burman, David G. Blair

摘要:

使用872个孤立的射电星的脉冲宽度数据,我们测试的假设,通过逐步缩小的发射锥相结合的自旋和磁轴的渐进对齐的射电星演变。新的数据提供了强有力的证据,在大约100万年的时间尺度上的对齐,在整个观察人口的对数标准差约为0.8。这个时间尺度比以前的作者发现的大约1000万年的时间尺度要短,但是对数标准差更大。结果与基于单独的磁场衰减或单调反向对准正交旋转的模型不一致。最好的拟合获得的制动指数参数n_gamma约等于2.3,一致的平均值的六个测量值,但基于一个更大的样本的年轻人。最小二乘拟合模型被用来预测作为日志特征年龄的函数的自旋和磁轴之间的平均倾角。将这些预测与现有的估计进行比较,可以发现,以随机倾斜角度出生的行星模型与数据最吻合。使用最佳拟合的模型参数的平均聚束分数作为特征年龄的函数的曲线图。

英文摘要:

Using pulsewidth data for 872 isolated radio pulsars we test the hypothesis that pulsars evolve through a progressive narrowing of the emission cone combined with progressive alignment of the spin and magnetic axes. The new data provide strong evidence for the alignment over a time-scale of about 1 Myr with a log standard deviation of around 0.8 across the observed population. This time-scale is shorter than the time-scale of about 10 Myr found by previous authors, but the log standard deviation is larger. The results are inconsistent with models based on magnetic field decay alone or monotonic counter-alignment to orthogonal rotation. The best fits are obtained for a braking index parameter n_gamma approximately equal to 2.3, consistent the mean of the six measured values, but based on a much larger sample of young pulsars. The least-squares fitted models are used to predict the mean inclination angle between the spin and magnetic axes as a function of log characteristic age. Comparing these predictions to existing estimates it is found that the model in which pulsars are born with a random angle of inclination gives the best fit to the data. Plots of the mean beaming fraction as a function of characteristic age are presented using the best-fitting model parameters.

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