Coherent Emission in Fast Radio Bursts

Abstract

The fast (ms) radio bursts reported by Thornton, {\it et al.} have extremely high brightness temperatures if at the inferred cosmological distances. This implies coherent emission by "bunches" of charges. We model the emission region as a screen of dipole radiators resonant at the frequency of observation and calculate the necessary charge bunching. From this we infer the minimum electron energy required to overcome electrostatic repulsion. The FRB, like the giant pulses of the Crab pulsar, display banded spectra that may be harmonics of plasma frequency emission by plasma turbulence. If FRB are the counterparts of comparatively frequent Galactic events, these may be detected by radio telescopes in their far sidelobes or by small arrays of dipoles.