A tidal disruption event (TDE) occurs when a supermassive black hole rips apart a passing star. Part of the stellar material falls toward the black hole, forming an accretion disk that in some cases launches a relativistic jet. We performed optical polarimetry observations of a TDE, AT 2020mot. We find a peak linear polarization degree of 25 ± 4%, consistent with highly polarized synchrotron radiation, as is typically observed from relativistic jets. However, our radio observations, taken up to 8 months after the optical peak, do not detect the corresponding radio emission expected from a relativistic jet. We suggest that the linearly polarized optical emission instead arises from shocks that occur during accretion disk formation, as the stream of stellar material collides with itself.

中文翻译：

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潮汐瓦解事件中碰撞恒星流激波产生的光偏振

当超大质量黑洞撕裂一颗路过的恒星时，就会发生潮汐瓦解事件 (TDE)。部分恒星物质落向黑洞，形成吸积盘，在某些情况下会发射相对论性喷流。我们对 AT 2020mot 的 TDE 进行了光学偏振观测。我们发现峰值线性偏振度为 25 ± 4%，与高度偏振的同步辐射一致，这通常是从相对论射流中观察到的。然而，我们在光学峰值后长达 8 个月的无线电观测没有检测到相对论射流预期的相应无线电发射。我们认为线性偏振光发射是由吸积盘形成过程中发生的冲击引起的，因为恒星物质流与自身发生碰撞。