What can we learn from FRB 200428?

TL;DR

This paper investigates whether the two radio pulses from SGR 1935+2154 are true FRBs or different phenomena, analyzing their features and implications for understanding fast radio bursts and magnetar activity.

Contribution

It clarifies the nature of the TRPs from SGR 1935+2154, distinguishing them from normal radio pulses and examining their relation to periodic FRBs.

Findings

TRPs are produced by different mechanisms than normal radio pulses.

TRPs are unlikely to be the same as periodically repeating FRBs.

Precession is unlikely to cause the periodicity in repeating FRBs.

Abstract

The two radio pulses (TRPs) from SGR 1935+2154 detected by \cite{BKRMHB} and \cite{2020arXiv200510324T} have similar features to that of cosmological fast radio bursts (FRBs). Many authors directly call the TRPs as FRB 200428 without consider two questions carefully. (1) Are the TRPs just two brighter subpulses of a normal radio pulse liking the normal radio pulses seen in other magnetars during their outburst? (2) If the TRPs are two bursts of an FRB, does this make other FRBs difficult to understand? In this paper, we try to clarify these two questions. First, we compare these TRPs with previous observations of normal radio pulses from pulsars and magnetars, and find that the TRPs should be produced by different mechanism from that of normal radio pulses. We then investigate the second question by assuming the TRPs have the same origin as that of periodically repeating FRBs and find that the origin of the periodicity of periodically repeating FRBs should not be induced by precession. Otherwise, we should expect that the TRPs are not an FRB, at least the TRPs don't have the same origin as that of periodically repeating FRBs.