http://arxiv.org/abs/2204.08124
Fast radio bursts (FRBs) are mysterious cosmic sources emitting millisecond-duration radio bursts\cite{Lorimer2007}. Although several hundreds FRBs have been discovered\cite{TheCHIME/FRBCollaboration2021}, their physical nature and central engine are still unclear\cite{Cordes2019,Petroff2019,Zhang2020,Xiao2021}. The variations of Faraday rotation measure and dispersion measure, due to local environment, are crucial clues to understand their physical nature\cite{Michilli2018,Anna-Thomas2022}. The recent observations on the rotation measure of FRB 20201124A show a significant variation on a daytime scale\cite{FAST21}. The variable rotation measure demonstrates that FRB 20201124A is in a dynamic magneto-ionic environment\cite{FAST21}. Intriguingly, the oscillation of rotation measure supports that the local contribution can change sign, which indicates the direction changes of the magnetic field along the line of sight. Here we propose that this FRB resides in a binary system containing a magnetar and a Be star with a decretion disk. When the magnetar approaches the periastron, the propagation of radio waves through the disk of the Be star naturally leads to the observed varying rotation measure, depolarization, large scattering timescale, and Faraday conversion. Searching for FRB signals from Be/X-ray binaries is encouraging.
F. Wang, G. Zhang, Z. Dai, et. al.
Tue, 19 Apr 22
17/52
Comments: 41 pages, 5 figures, submitted on Dec. 1, 2021
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