Journal Article

Repeating fast radio burst 20201124A originates from a magnetar/Be star binary

Dai, Z. G., Zhang, G. Q., Wang, F. Y., Cheng, K. S.

2022

Overview

Fast radio bursts (FRBs) are cosmic sources emitting millisecond-duration radio bursts. Although several hundreds FRBs have been discovered, their physical nature and central engine remain unclear. The variations of Faraday rotation measure and dispersion measure, due to local environment, are crucial clues to understanding their physical nature. The recent observations on the rotation measure of FRB 20201124A show a significant variation on a day time scale. Intriguingly, the oscillation of rotation measure supports that the local contribution can change sign, which indicates the magnetic field reversal along the line of sight. Here we present a physical model that explains observed characteristics of FRB 20201124A and proposes that repeating signal comes from 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. This study will prompt to search for FRB signals from Be/X-ray binaries. Fast radio bursts (FRBs) are bright millisecond or shorter duration transient events. Here, the authors propose that FRB 20201124A comes from a binary system of a magnetar and a Be star with a decretion disk.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/33/34/4121 / 639/33/34/4127 / 639/33/34/864 / Astronomy / B stars / Binary stars / Depolarization / Faraday effect / Humanities and Social Sciences / Magnetars / Magnetic fields / multidisciplinary / Neutron stars / Radio bursts / Radio waves / Science / Science (multidisciplinary) / Supernovae / Wave propagation / X ray binaries / X ray stars