Subjects: Astronomy submitted time 2024-04-12 Cooperative journals: 《天文学报》
WEN Zhi-gang
WANG Na
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WANG Hong-guang
CHEN Jian-ling
YUAN Jian-ping
YUEN Rai
YAN Wen-ming
TOKTONUR Ergesh
CUI Si-ran
LI Jian
LYU Cheng-bing
Abstract： We study the waiting time distribution of giant pulses from the Crab pulsar observed with the Nanshan 26-m radio telescope at a center frequency of 1556\;MHz with 512 MHz bandwidth. The observations were performed over a duration of 12.6 hours with 32\;$\upmu$s sampling interval. Our analysis has led to the detection of 2097 giant pulses above a threshold of 10 $\sigma$, with flux density $>$ 100\;Jy. The occurrence rate of giant pulses is characterized by a highly intermittent giant pulse productivity in short clusters with high rates, separated by relatively long quiescent intervals with low occurrence rates, especially for the giant pulses associated with the interpulse emission. The distribution of waiting times between two subsequent giant pulses displays a power-law tail and can be modeled with a non-stationary Poisson process, which indicates that giant pulses are independent and random events. Distinct waiting time distributions between giant pulses in the main pulse and interpulse phases are presented, which implies that the giant pulse emission mechanisms maybe different in the opposite magnetic poles. The ramification for our understanding of the radio emission mechanisms is discussed.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-04-13 Cooperative journals: 《天文研究与技术》
Abstract： 本文利用公开数据研究了PSR J1906+0746的主脉冲和中间脉冲的辐射特征。通过对各段时期的平均脉冲轮廓进行高斯拟合，得到了对应的10%峰值脉冲宽度和峰值流量密度，进而研究了其与碰撞角之间的关系。结果表明主脉冲辐射束的主要可见部分可由一束有确定磁经度角范围的磁流管产生，而中间脉冲则来自于环绕磁轴的磁力线上的辐射。现有的扇形束模型可以较好的解释主脉冲的特征，但难以解释中间脉冲的辐射特征。中间脉冲的特征要求改进扇形束模型，在假设磁轴四周的磁力线均有辐射的情况下，通过合理选择模型参数来模拟观测到的条形辐射束。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-05-07 Cooperative journals: 《天文研究与技术》
Abstract： 年轻脉冲星PSR J0614+2229是少数模式变换时发生相位偏移的脉冲星之一。本文利用Parkes射电天文台的10 cm、20 cm和50 cm三个波段上的偏振观测数据，对每个波段爆发模式和正常模式的线偏振位置角用旋转矢量模型进行拟合，确定了其最大斜率点的相位差。进而利用广泛使用的确定辐射高度的相对论性方法，首次得到了模式变换时辐射高度的变化，发现正常模式的辐射位置高于爆发模式，其高度差随着频率增加而扩大。根据两个模式累积脉冲窗口中心的相位差，可以推断两个模式的辐射区并不都关于磁轴-自转轴所在子午面对称。
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