双成分星际介质的折射闪烁

REFRACTIVE SCINTILLATIONS BY TWO-COMPOWENT INTERSTELLAR MEDIUM

本文用比较严格的理论讨论了由连续介质和散射薄屏组成的星际介质对河外射电源的折射闪烁．对折射闪烁引起的流量变化的结构函数Ｄ（τ）（τ为迟后时间）的计算表明，结构函数的幂律部份的指数Ｐ（Ｄ（τ）（∝τＰ）依赖于上述两个成份的相对散射强度，即在连续介质散射为主的情况下；而在薄屏散射为主的情况下；若两个成份的散射可相比较时，１＜Ｐ＜２．因此本模型可以用于解释在河外射电源和脉冲星中观测到的折射闪烁的结构函数具有不同幂指数的情形，特别是Ｐ～１．５的情形．

In thes paper a rigorous treatment of the refractive sintillations of extragalactic radio sourses caused by a two-component interstellar medium is discussed. It is assumed that the interstellar medium is composed of a thin screen and a continuous medium. The structure functions D(τ) of flux variations caused by refractive scintillations are calculated. It is shown that the power-law index p (D(τ)∝τp) of the structure function depends on the relative scattering strength of the thin screen and the continuous medium. If the sattering by the continuous medium is dominating, then p=1. Inversely, if the scattering of the thin screen dominates, p=2. When the scattering by the screen and that by the continuous medium are comparable, we have 1<p<2. Therefore, the propose model can be applied to interplay the different hoes of structure functions observed in extragalactic radio sources and in pulsars, especially in the case of .