The Integrated Pulse Profiles of Fast Radio Bursts

TL;DR

This paper proposes that the multi-peaked pulse profiles of fast radio bursts are caused by interference-like spectra near the source, explained by electron bunching and plasma wakefield acceleration.

Contribution

It introduces a novel interpretation linking burst profiles to instantaneous spectra from electron bunches, emphasizing the role of plasma wakefield acceleration.

Findings

Pulse profiles are linked to instantaneous spectra near the source.

Multi-peaked spectra are explained by electron bunching effects.

Spectrum visibility depends on particle bunching in the radiation beam.

Abstract

Multi-peaked features appear on the integrated pulse profiles of fast radio burst observed below 2.5 GHz and the instantaneous spectrum of many bursts observed between 4 and 8 GHz. The mechanism of pulse or spectrum shaping has attracted little attention. Here we show that these interference-like pulse profiles are mostly the instantaneous spectra near the source regions of fast radio bursts. The corresponding instantaneous spectra are coincident to the spectrum from a single electron passing through a tapered undulator. The multi-peaked spectrum observed between 4 and 8 GHz can also be explained consistently by this type of spectrum. The spectrum is invisible unless the particles in the radiation beam are bunched. The bunching effect is probably due to the acceleration of particles in the plasma wakefield.