Three aspects of the radius-to-frequency mapping in fast radio bursts

Abstract

ABSTRACT We have explored the radius-to-frequency mapping further in cases of fast radio bursts (FRBs). We present an analytical treatment of Lyutikov (2020, ApJ, 889, 135). We obtain the frequency dependence of the drifting rate and the drifting time-scale. The aberration effect and the twist of the magnetic field lines can result in drifting in both directions. For one FRB, the burst width is larger at a lower frequency, according to the radius-to-frequency mapping. For the FRB population, the magnetic fields of the repeaters might be larger than those of the non-repeaters. Then, according to the radius-to-frequency mapping, the burst widths of the repeaters will be wider than those of the apparent non-repeaters. If a similar window function (or emission cones) as for pulsars and magnetars is also at work in the case of FRBs, then the window function might explain the single or multiple components of FRB profiles. The modelling of the radius-to-frequency mapping is, to some degree, independent of the underlying radio emission mechanism.