Repeating X-ray bursts: Interaction between a neutron star and clumps partially disrupted from a planet

¹ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, 830011 Xinjiang, PR China
e-mail: akurban@xao.ac.cn; na.wang@xao.ac.cn; zhouxia@xao.ac.cn
² Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi, 830011 Xinjiang, PR China
³ Xinjiang Key Laboratory of Radio Astrophysics, Urumqi, 830011 Xinjiang, PR China
⁴ School of Astronomy and Space Science, Nanjing University, Nanjing 210023, PR China
⁵ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210023, PR China
⁶ School of Physics and Electronic Engineering, Sichuan University of Science & Engineering, Zigong 643000, PR China

Received: 30 August 2023
Accepted: 12 March 2024

Abstract

Repeating X-ray bursts from the Galactic magnetar SGR 1806-20 have been observed with a period of 398 days. Similarly, periodic X-ray bursts from SGR 1935+2154 with a period of 238 days have also been observed. Here we argue that these X-ray bursts could be produced by the interaction of a neutron star (NS) with its planet in a highly elliptical orbit. The periastron of the planet is very close to the NS, so it would be partially disrupted by the tidal force every time it passes through the periastron. Major fragments generated in the process will fall onto the NS under the influence of gravitational perturbation. The collision of the in-falling fragments with the NS produces repeating X-ray bursts. The main features of the observed X-ray bursts, such as their energy, duration, periodicity, and activity window, can all be explained in our framework.