Strong scintillations in astrophysics. I - The Markov approximation, its validity and application to angular broadening
Strong scintillations in astrophysics. I - The Markov approximation, its validity and application to angular broadening
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天体物理学中的强闪烁。
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
J. R. Jokipii
中科院分区：
文献类型：
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作者：
Lou‐Chuang Lee;J. R. Jokipii
在天体物理学的背景下讨论了波在扩展的不规则介质中传播的马尔可夫近似。本文提出了一种新的推导方法，该方法简单，证明了以前作者使用的高斯统计假设是不相关的。我们讨论了近似的相关性，并表明它可以应用于许多感兴趣的情况，包括脉冲星信号的星际闪烁。该近似不需要假设弱散射或高斯相关函数。角谱的马尔可夫方程特别简单，并讨论了典型湍流谱的解。我们发现角谱方程与前人所使用的公式非常接近，并且本文的讨论表明，这些结果比以前认为的要普遍得多。讨论了区分高斯和幂律星际密度谱的一种可能的观测检验。
The Markov approximation to the propagation of waves in an extended, irregular medium is discussed in an astrophysical context. A new derivation is presented which is simple and which shows that the assumption of Gaussian statistics used by previous authors is irrelevant. We discuss the relevance of the approximation and show that it may apply in many situations of interest, including interstellar scintillations of pulsar signals. The approximation does not require the assumption of weak scattering or Gaussian correlation functions. The Markov equation for the angular spectrum is particularly simple, and solutions are discussed for typical turbulence spectra. It is found that the equation for the angular spectrum is very nearly that used by previous authors, and the present discussion shows that these results are much more general than previously thought. A possible observational test for distinguishing between Gaussian and power-law interstellar density spectra is discussed.