论文标题
伽马射线脉冲星的单个脉冲变异性
Single Pulse Variability in Gamma-ray Pulsars
论文作者
论文摘要
费米大面积望远镜从任何$γ$ -Ray pulsar获得$ \ ll $ 1光子。然而，在数十亿个明亮的脉冲星Vela（PSR〜J0835 $ - $ 4510）和Geminga（PSR〜J0633 $+$ 1746）的旋转中，几千美元具有$ \ geq $ 2脉冲光子。这些罕见的对编码有关脉冲振幅和形状可变性的信息。我们已经分类了这样的对，并发现观察到的数字与简单的泊松统计符合良好的一致性，将任何振幅变化限制为$ <$ 19％（VELA）和$ <$ 22％（geminga），以2 $σ$信心。使用基本函数来建模脉冲形状变异性，对配对的观察到的脉冲相分布限制了Vela的脉冲形状变化的比例为$ <$ 13％，而对于Geminga来说，我们发现$ \ sim $ \ sim $ 20％的单脉冲形状变异性与脉搏峰最相关。如果变化持续的持续时间比单轮旋转更长，则可以收集更多的对，并且我们计算了上幅度和形状变化的上限，假定的相干时间最多100旋转，发现$ \ sim $ 1％（振幅）和$ \ sim $ 3％（Shape）的限制。由于大量的脉冲星磁层有助于$γ$ -Ray脉冲的产生，因此我们得出结论，这两个能量脉冲星的磁层在一个旋转上是稳定的，并且在更长的时间尺度上非常稳定。所有其他$γ$ ray脉冲星太微弱，无法进行类似的分析。这些结果为脉冲星的快速改进模拟提供了有用的限制，这些模拟在薄赤道电流板上揭示了各种大规模的不稳定性，其中大部分GEV $γ$ ray-ray-ray发射被认为是起源的。
The Fermi Large Area Telescope receives $\ll$1 photon per rotation from any $γ$-ray pulsar. However, out of the billions of monitored rotations of the bright pulsars Vela (PSR~J0835$-$4510) and Geminga (PSR~J0633$+$1746), a few thousand have $\geq$2 pulsed photons. These rare pairs encode information about the variability of pulse amplitude and shape. We have cataloged such pairs and find the observed number to be in good agreement with simple Poisson statistics, limiting any amplitude variations to $<$19% (Vela) and $<$22% (Geminga) at 2$σ$ confidence. Using an array of basis functions to model pulse shape variability, the observed pulse phase distribution of the pairs limits the scale of pulse shape variations of Vela to $<$13% while for Geminga we find a hint of $\sim$20% single-pulse shape variability most associated with the pulse peaks. If variations last longer than a single rotation, more pairs can be collected, and we have calculated upper limits on amplitude and shape variations for assumed coherence times up to 100 rotations, finding limits of $\sim$1% (amplitude) and $\sim$3% (shape) for both pulsars. Because a large volume of the pulsar magnetosphere contributes to $γ$-ray pulse production, we conclude that the magnetospheres of these two energetic pulsars are stable over one rotation and very stable on longer time scales. All other $γ$-ray pulsars are too faint for similar analyses. These results provide useful constraints on rapidly-improving simulations of pulsar magnetospheres, which have revealed a variety of large-scale instabilities in the thin equatorial current sheets where the bulk of GeV $γ$-ray emission is thought to originate.
