Formation Channels of Magnetars

TL;DR

This paper investigates the formation channels of magnetars, emphasizing the significant role of binary interactions through population synthesis simulations, and analyzes their properties, origins, and observational signatures.

Contribution

It introduces a comprehensive simulation-based analysis of magnetar formation channels, highlighting the importance of binary evolution and providing testable predictions.

Findings

Majority of magnetars are observed as single objects.

Many magnetars originate from binary systems with possible mergers or kicks.

Binary evolution influences the orbital properties and companion types 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, analyze the orbital properties and companion types of surviving magnetar binaries. We find that the majority of magnetars are observed as single objects ($\geq 90\%$), although a large fraction of them were originally in binary systems and experienced either 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.