Magnetars origin and progenitors with enhanced rotation

TL;DR

This paper uses population synthesis to estimate the fraction of magnetars originating from rapidly rotating progenitors, finding most are isolated due to binary disruptions, with few remaining in binaries, often with black hole companions.

Contribution

It provides a theoretical estimate of the fraction of magnetars formed from progenitors with enhanced rotation and analyzes their binary status and potential companions.

Findings

13-16% of neutron stars originate from rapidly rotating progenitors.

Most such neutron stars are isolated due to binary coalescence or disruption.

Less than 1% of these neutron stars remain in binaries, often with black hole companions.

Abstract

Among a dozen known magnetar candidates there are no binary objects. As an estimate of a fraction of binary neutron stars is about 10% it is reasonable to address the question of solitarity of magnetars, to estimate theoretically the fraction of binary objects among them, and to mark o probable companions. We present population synthesis calculations of binary systems. Our goal is to estimate the number of neutron stars originated from progenitors with enhanced rotation, as such compact objects can be expected to have large magnetic fields, ie. they can be magnetars. The fraction of such neutron stars in our calculations is about 13-16%. Most of these objects are isolated due to coalescences of components prior to a neutron star formation, or due to a system disruption after a supernova explosion. The fraction of such neutron stars in survived binaries is about 1% or lower. Their most numerous companions are black holes.