AR Sco as a possible seed of highly magnetised white dwarf

TL;DR

This paper investigates how repeated accretion and spin-down episodes could produce highly magnetized white dwarfs like AR Sco, potentially explaining their properties and their role in supernovae and gravitational wave sources.

Contribution

It proposes a cyclical accretion and spin-down process as a mechanism for forming highly magnetized white dwarfs like AR Sco, linking them to supernovae and gravitational radiation.

Findings

Repeated accretion and spin-down can produce high magnetic field white dwarfs.

High magnetic white dwarfs may be sources of gravitational radiation.

Cycle of accretion and spin-down explains AR Sco's properties.

Abstract

We explore the possibility that the recently discovered white dwarf pulsar AR Sco acquired its high spin and magnetic field due to repeated episodes of accretion and spin-down. An accreting white dwarf can lead to a larger mass and consequently a smaller radius thus causing an enhanced rotation period and magnetic field. This spinning magnetic white dwarf temporarily can inhibit accretion, spin down, and, eventually, the accretion can start again due to the shrinking of the binary period by gravitational radiation. A repeat of the above cycle can eventually lead to a high magnetic field white dwarf, recently postulated to be the reason for over-luminous type Ia supernovae. We also point out that these high magnetic field spinning white dwarfs are attractive sites for gravitational radiation.