On the origin of the radio emission of a tidal disruption event candidate

A simple analysis of the radio light curve of the tidal disruption event candidate Sw J1644+57 shows that the energy of the radio-emitting electrons increases by a factor of 20 over a period of about 200 days. There is no clear explanation to the origin of this additional energy and why it is not observed in any other energy band. Using simple equipartition arguments, we find that the data requires either: 1. a continuous energy supply to the blast wave that increases the total energy of the emitting electrons by a factor of twenty or 2. a constant energy reservoir with time-varying microphysics. In the context of the last option, we show that the Inverse Compton (IC) cooling of the radio-emitting electrons caused by their interaction with the X-ray photons can lead to an effective change in the microphysics parameters that explains the observed radio light curve. As the X-ray flux decreases, so does the IC cooling, and this yields both an effective increase in the energy in the synchrotron-emitting electrons and an apparent increase in the total energy, favorably reproducing the observed radio data.

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