PSR B0329 +54中4.8 GHz下的衍射和折射时间尺度
Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54
摘要：
本文介绍了利用32米TCfA射电望远镜在4.8 GHz频率上对PSR B 0329 +54的通量密度监测结果。这些观察是在2002年至2005年期间进行的。该项目的主要目标是找到脉冲星在从未详细研究过的频率下的星际闪烁（ISS）参数。为了实现这一目标，20次观察会议包括3分钟的整合，平均持续24小时。使用结构函数分析了每个会话获得的通量密度时间序列。对于一些单独的会话以及一般的平均结构函数，我们能够识别出两个不同的时间尺度，衍射和折射衍射的时间尺度。据我们所知，这是第一次在一个统一的数据集中同时观察到两个闪烁时标，t_DISS=42.7分钟和t_RISS=305分钟，并使用相同的方法进行估计。所获得的ISS参数值与文献中发现的数据相结合，使我们能够研究这些参数在很宽的观测频率范围内的频率依赖性，这对于理解ISM湍流至关重要。我们发现Kolmogorov谱并不适合描述ISM的密度波动，β =4的幂律谱似乎更适合我们的结果。我们还能够估计的过渡频率（从强到弱闪烁制度的过渡）为10.1 GHz，远远高于以前的预测。我们还能够估计散射参数u=2.67$的强度和菲涅耳尺度为6.7x10^8米。
英文摘要：
We present the results of flux density monitoring of PSR B0329+54 at the frequency of 4.8 GHz using the 32-meter TCfA radiotelescope. The observations were conducted between 2002 and 2005. The main goal of the project was to find interstellar scintillation (ISS) parameters for the pulsar at the frequency at which it was never studied in detail. To achieve this the 20 observing sessions consisted of 3-minute integrations which on average lasted 24 hours. Flux density time series obtained for each session were analysed using structure functions. For some of the individual sessions as well as for the general average structure function we were able to identify two distinctive timescales present, the timescales of diffractive and refractive scintillations. To the best of our knowledge, this is the first case when both scintillation timescales, t_DISS=42.7 minutes and t_RISS=305 minutes, were observed simultaneously in a uniform data set and estimated using the same method. The obtained values of the ISS parameters combined with the data found in the literature allowed us to study the frequency dependence of these parameters over a wide range of observing frequencies, which is crucial for understanding the ISM turbulence. We found that the Kolmogorov spectrum is not best suited for describing the density fluctuations of the ISM, and a power-law spectrum with beta =4 seems to fit better with our results. We were also able to estimate the transition frequency (transition from strong to weak scintillation regimes) as 10.1 GHz, much higher than was previously predicted. We were also able to estimate the strength of scattering parameter u=2.67$ and the Fresnel scale as 6.7x10^8 meters.
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