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arXiv 0704.1197astro-ph
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蟹状星云脉冲星巨脉冲的统计特性

Statistical properties of giant pulses from the Crab pulsar

M. V. Popov, B. Stappers

摘要:

我们首次研究了蟹状星云脉冲星巨脉冲的统计特性,特别是脉冲宽度。我们分析了在3.5小时的观测与韦斯特博克综合射电望远镜在捆绑阵列模式下,在1200兆赫的频率进行的数据。PuMa脉冲星后端在两个共轭10 MHz波段提供X和Y线性偏振态的电压记录。我们将时间分辨率限制为4微秒,以匹配星际不均匀性的散射。在总共约18000巨脉冲(GP)检测到的全强度与6西格玛的阈值水平。巨脉冲能量的累积概率分布(CPD)进行了分析,不同的有效宽度在4至65微秒的范围内的GP组。不同GP宽度组的CPD存在显著差异。当从最短GP到最长GP时,CPD的高能量部分的幂律拟合的斜率从-1.7演变到-3.2。在CPD幂律拟合中存在中断,表明在低能量处变平,短和长GP的指数分别为-1.0至-1.9。具有较强峰值通量密度的GP被发现具有较短的持续时间。我们将我们的结果与以前发表的数据进行比较,并讨论了这些特点的重要性,在统计特性的GP负责GP生成的发射机制的理论理解。

英文摘要:

We have studied the statistics of giant pulses from the Crab pulsar for the first time with particular reference to their widths. We have analyzed data collected during 3.5 hours of observations conducted with the Westerbork Synthesis Radio Telescope operated in a tied-array mode at a frequency of 1200 MHz. The PuMa pulsar backend provided voltage recording of X and Y linear polarization states in two conjugate 10 MHz bands. We restricted the time resolution to 4 microseconds to match the scattering on the interstellar inhomogeneities. In total about 18000 giant pulses (GP) were detected in full intensity with a threshold level of 6 sigma. Cumulative probability distributions (CPD) of giant pulse energies were analyzed for groups of GPs with different effective widths in the range 4 to 65 microseconds. The CPDs were found to manifest notable differences for the different GP width groups. The slope of a power-law fit to the high-energy portion of the CPDs evolves from -1.7 to -3.2 when going from the shortest to the longest GPs. There are breaks in the CPD power-law fits indicating flattening at low energies with indices varying from -1.0 to -1.9 for the short and long GPs respectively. The GPs with a stronger peak flux density were found to be of shorter duration. We compare our results with previously published data and discuss the importance of these peculiarities in the statistical properties of GPs for the heoretical understanding of the emission mechanism responsible for GP generation.

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