标题： 1540 MHz下五颗脉冲星的长期闪烁观测 显示英文标题

标题： Long-term Scintillation Observations of Five Pulsars at 1540 MHz

摘要： 2001年1月至2002年6月期间，我们利用乌鲁木齐天文台南山25米射电望远镜监测了PSR B0329+54、B0823+26、B1929+10、B2020+28和B2021+51，以研究它们的衍射式星际闪烁（DISS）现象。观测平均间隔约为9天，持续时间因脉冲星而异，在2到6小时之间。在18个月的数据跨度内，我们观察到了DISS参数的广泛变化。尽管如此，平均闪烁速度与视向速度非常一致。对于PSR B0329+54，其平均二维自相关函数可以用薄屏Kolmogorov模型很好地描述，至少沿时间和频率轴是这样。DISS时间尺度和带宽以及脉冲星流量密度的观测调制指数大于Kolmogorov电子密度涨落谱预测的值。我们观察到比名义折射性闪烁时间长得多的时间上的相关变化，表明较大尺度的密度涨落很重要。对于这些脉冲星，闪烁带宽作为频率的函数具有幂律指数（约3.6），远小于预期的Kolmogorov湍流（约4.4）。动态谱中通常可以观察到倾斜条纹，特别是对于PSR B0329+54。检测到的条纹斜率范围受到我们的观测分辨率限制。我们的观测对更大尺度的条纹敏感，因此对应较小的折射角，这对应于散射盘的中心部分。 显示英文摘要

摘要： From 2001 January to 2002 June, we monitored PSRs B0329+54, B0823+26, B1929+10, B2020+28 and B2021+51 using the Nanshan 25-m radio telescope of Urumqi Observatory to study their diffractive interstellar scintillation (DISS). The average interval between observations was about 9 days and the observation duration ranged between 2 and 6 hours depending on the pulsar. Wide variations in the DISS parameters were observed over the 18-month data span. Despite this, the average scintillation velocities are in excellent agreement with the proper motion velocities. The average two-dimensional autocorrelation function for PSR B0329+54 is well described by a thin-screen Kolmogorov model, at least along the time and frequency axes. Observed modulation indices for the DISS time scale and bandwidth and the pulsar flux density are greater than values predicted for a Kolmogorov spectrum of electron density fluctuations. Correlated variations over times long compared to the nominal refractive scintillation time are observed, suggesting that larger-scale density fluctuations are important. For these pulsars, the scintillation bandwidth as a function of frequency has a power-law index (~3.6) much less than expected for Kolmogorov turbulence (~4.4). Sloping fringes are commonly observed in the dynamic spectra, especially for PSR B0329+54. The detected range of fringe slopes are limited by our observing resolution. Our observations are sensitive to larger-scale fringes and hence smaller refractive angles, corresponding to the central part of the scattering disk.