In the paper we study propagation of light in general relativity through a spacetime filled with cold plasma with infinite conductivity. We use the geometric optics based on Synge's approach. As the main result we provide a formula for calculation of spectral flux of radiation emitted from a pointlike source. The formula employs connecting vectors that are obtained by integrating the ray deviation equation along the reference ray connecting the source and observation event. As a byproduct we formulate Etherington's reciprocity theorem with the inclusion of plasma, interrelating angular size distance and luminosity distance. We also discuss the Liouville theorem and its formulation in terms of connecting vectors.

中文翻译：

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广义相对论中点状源的辐射通量

在这篇论文中，我们研究了广义相对论中光在充满冷等离子体的时空中的传播，该等离子体具有无限的导电性。我们使用基于 Synge 方法的几何光学。作为主要结果，我们提供了一个计算从点状源发射的辐射的光谱通量的公式。该公式采用连接向量，这些连接向量是通过沿着连接源和观测事件的参考射线对射线偏差方程进行积分而获得的。作为副产品，我们制定了包含等离子体、相互关联的角尺寸距离和光度距离的 Etherington 互易定理。我们还讨论了 Liouville 定理及其在连接向量方面的公式。