The evolution of a newborn millisecond magnetar with a propeller-recycling disk

TL;DR

This paper models the evolution of a newborn millisecond magnetar interacting with a propeller-recycling disk, revealing how disk dynamics influence the magnetar's spin-down and magnetic field evolution, impacting early and late transient emissions.

Contribution

It introduces a new model of NS evolution involving a propeller-recycling disk, showing how it affects spin-down and magnetic field suppression over time.

Findings

Propeller effect initially dominates NS spin-down.

Abrupt disk fallback can suppress magnetic dipole radiation.

NS can transition from normal to low-field magnetar.

Abstract

A rapidly rotating and highly magnetized neutron star (NS) could be formed from the explosive phenomena such as superluminous supernovae and gamma-ray bursts. This newborn NS can substantially influence the emission of these explosive transients through its spin-down. The spin-down evolution of the NS can sometimes be affected by fallback accretion, although it is usually regulated by the magnetic dipole radiation and gravitational wave radiation of the NS. Under appropriate conditions, the accreting material can be firstly ejected and subsequently recycled back, so that the accretion disk can keep in a quasi-steady state for a long time. Here we describe the interaction of the NS with such a propeller-recycling disk and their co-evolution. Our result shows that, the spin-down of the NS can be initially dominated by the propeller, which prevents the disk material from falling onto the NS until hundreds or thousands of seconds later. It is suggested that the abrupt fall of the disk material onto the NS could significantly suppress the magnetic dipole radiation and then convert the NS from a normal magnetar to a low-field magnetar. This evolution behavior of the newborn NS can help to understand the very different influence of the NS on the early GRB afterglows and the late supernova/kilonova emission.