Magnetic fields of exoplanets are important in shielding the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both cyclotron and synchrotron radio emissions, of which neither has been definitely identified in observations yet. As the coherent cyclotron emission has been extensively studied in literatures, here we focus on the planetary synchrotron radiation with bursty behaviors (i.e., radio flares) caused by the outbreaks of energetic electron ejections from the host star. Two key parameters of the bursty synchrotron emissions, namely the flux density and burst rate, and two key features namely the burst light curve and frequency shift, are predicted for star - hot Jupiter systems. The planetary orbital phase - burst rate relation is also considered as the signature of star-planet interactions (SPI). As examples, previous X-ray and radio observations of two well studied candidate systems, HD 189733 and V830 \tau, are adopted to predict their specific burst rates and fluxes of bursty synchrotron emissions for further observational confirmations. The detectability of such emissions by current and upcoming radio telescopes shows that we are at the dawn of discoveries.

中文翻译：

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系外行星同步加速器射电爆发的观测特征

系外行星的磁场对于保护行星免受宇宙射线和行星际等离子体的影响很重要。由于与来自宿主恒星的电子的相互作用，预计系外行星磁层将同时具有回旋加速器和同步加速器无线电发射，但在观测中尚未明确确定这两者。由于相干回旋辐射已在文献中得到广泛研究，这里我们重点讨论由主星高能电子喷射爆发引起的具有突发行为（即射电耀斑）的行星同步辐射。预测了恒星-热木星系统的突发同步加速器发射的两个关键参数，即通量密度和突发速率，以及两个关键特征，即突发光变曲线和频移。行星轨道相位-爆发率关系也被认为是星-行星相互作用（SPI）的特征。例如，之前对两个经过充分研究的候选系统 HD 189733 和 V830 \tau 的 X 射线和无线电观测被用来预测它们的特定爆发率和同步加速器发射的通量，以进行进一步的观测确认。当前和即将推出的射电望远镜对此类发射的可探测性表明，我们正处于发现的曙光之中。