In a supernova explosion, the ejecta interacting with the surrounding circumstellar medium (CSM) give rise to variety of radiation. Since CSM is created from the mass loss from the progenitor, it carries footprints of the late time evolution of the star. This is one of the unique ways to get a handle on the nature of the progenitor system. Here, I will focus mainly on the supernovae (SNe) exploding in dense environments, a.k.a. Type IIn SNe. Radio and X-ray emission from this class of SNe have revealed important modifications in their radiation properties, due to the presence of high density CSM. Forward shock dominance in the X-ray emission, internal free-free absorption of the radio emission, episodic or non-steady mass loss rate, and asymmetry in the explosion seem to be common properties of this class of SNe.

中文翻译：

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密集环境中超新星的环星相互作用——观察视角

在超新星爆炸中，喷射物与周围星周介质 (CSM) 相互作用会产生各种辐射。由于 CSM 是由祖先的质量损失产生的，因此它带有恒星晚期演化的足迹。这是了解祖先系统性质的独特方法之一。在这里，我将主要关注在密集环境中爆炸的超新星 (SNe)，即 IIn SNe 型。由于高密度 CSM 的存在，来自此类超新星的无线电和 X 射线发射揭示了其辐射特性的重要改变。X 射线发射中的前向冲击优势、无线电发射的内部自由吸收、偶发性或非稳态质量损失率以及爆炸中的不对称性似乎是此类超新星的常见特性。