Formation Channels of Magnetars

Abstract The formation channels of magnetars remain an open question. Although core-collapse supernovae of isolated massive stars are important, binary interactions—such as tidal interaction, common envelope evolution, and stellar mergers—may also play a significant role in making magnetars. Understanding the relative contributions of these channels is crucial for linking magnetars to their observed properties and host environments. In this paper, we investigate potential magnetar formation channels using population synthesis simulations, considering both single-star and isolated binary system evolution. By conducting simulations with different parameters, we compare the effects of various evolution processes on magnetar formation. Additionally, we study the delay times and kick velocities across all formation channels, and analyze the orbital properties and companion types of surviving magnetar binaries. We find that the majority of magnetars are observed as single objects (≥90%), although a large fraction of them were originally in binary systems and experienced either a kick disruption or merger. Surviving binaries are most likely to host main-sequence companions and exhibit different distributions of eccentricities due to different supernova mechanisms. These findings show the critical role of binary evolution in magnetar formation and provide predictions for the properties of magnetar populations that can be tested with future observations.