Observational Features of Exoplanetary Synchrotron Radio Bursts

Abstract

The magnetic fields of exoplanets shield 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, neither of which have been definitively identified in observations. As the coherent cyclotron emission has been extensively studied in the literature, here we focus on 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. As examples, previous X-ray and radio observations of two well-studied candidate systems, HD 189733 and V830 τ, 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.

A Candidate Period of 4.605 Days for FRB 20121102A and One Possible Implication of Its Origin

“…Magnetic reconnection also occurs between the magnetar and the close-by planet if the planet is magnetized. Such reconnection can be modulated by the orbit of the planet, i.e., maximized when the strong magnetic field in the asymmetric planet magnetosphere faces the spinning magnetar (see Gao et al 2020), leading to the 4.605 day quasi-period. The second alternative is unipolar induction.…”

FAST: Its Scientific Achievements and Prospects

“…It is also proposed to study radio emissions from the interaction between the erupted plasma from a star and the magnetic field of the planets around the stars. 27 This would be an analysis of the flux distribution on the time (orbital phase)-frequency plane.…”