Multiwavelength radiation from the interaction between magnetar bursts and a companion star in a binary system

¹ Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, PR China
e-mail: dmwei@pmo.ac.cn
² School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
³ South-Western Institute for Astronomy Research, Yunnan University, Kunming 650504, PR China
e-mail: ypyang@ynu.edu.cn
⁴ Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, PR China
⁵ Department of Astronomy, School of Physical Sciences, University of Science and Technology of China, Hefei 230026, PR China
e-mail: daizg@ustc.edu.cn

Received: 1 December 2023
Accepted: 15 May 2024

Abstract

Magnetars are young, highly magnetized neutron stars that are associated with magnetar short bursts (MSBs), magnetar giant flares (MGFs), and at least some fast radio bursts (FRBs). In this work, we consider a magnetar and a main sequence star in a binary system and analyze the properties of the electromagnetic signals generated by the interaction between the magnetar bursts and the companion star. During the preburst period, persistent radiation could be generated by the interaction between the e⁺e⁻-pair wind from the magnetar and the companion or its stellar wind. We find that for a newborn magnetar, the persistent preburst radiation from the strong magnetar wind can be dominant, and it is mainly at the optical and ultraviolet (UV) bands. For relatively old magnetars, the re-emission from a burst interacting with the companion is larger than the persistent preburst radiation and the luminosity of the companion itself. The transient re-emission produced by the heating process has a duration of 0.1 − 10⁵ s at the optical, UV, and X-ray bands. Additionally, we find that if these phenomena occur in nearby galaxies within a few hundred kiloparsecs, they could be detected by current or future optical telescopes.