Coherent curvature radiation and Fast Radio Bursts

Gabriele Ghisellini, Nicola Locatelli

Published 2017-08-24Version 1

Fast radio bursts are extragalactic radio transient events lasting a few milliseconds, with a ~Jy flux at $\sim$1 GHz. We propose that these properties suggest a neutron star progenitor, and focus on coherent curvature radiation as the radiation mechanism. Even if the emission is coherent, we find that self--absorption can limit the produced luminosities, and study for what sets of parameters the emission can fulfill the observational constraints. Self--absorption severely limits the luminosities at low radio frequency, while coherence favours steep optically thin spectra. Furthermore, in order to obtain coherent curvature emission, the geometrical setup must have a high degree of order. Particles emit photons along their velocity vectors, greatly reducing the inverse Compton mechanism. In this case we predict that fast radio bursts emit most of their luminosities in the radio band, with no strong counterpart in any other frequency bands.