AR Scorpii and possible gravitational wave radiation from pulsar white dwarfs

TL;DR

This paper models highly magnetized, fast-rotating white dwarfs like AR Scorpii to evaluate their potential as detectable sources of gravitational waves for future space-based observatories.

Contribution

It provides self-consistent relativistic models of magnetized white dwarfs and estimates their gravitational wave emission, linking observations of AR Scorpii to GW detection prospects.

Findings

AR Scorpii can produce gravitational waves within DECIGO and BBO sensitivity bands.

Magnetic fields induce anisotropic pressures affecting star shape and GW emission.

White dwarf models suggest possible GW detection from pulsar-like white dwarfs.

Abstract

In view of the new recent observation and measurement of the rotating and highly-magnetized white dwarf AR Scorpii \cite{Marsh:2016uhc}, we determine bounds of its moment of inertia, magnetic fields and radius. Moreover, we investigate the possibility of fast rotating and/or magnetized white dwarfs to be source of detectable gravitational wave (GW) emission. Numerical stellar models at different baryon masses are constructed. For each star configuration, we compute self-consistent relativistic solutions for white dwarfs endowed with poloidal magnetic fields by solving the Einstein-Maxwell field equations in a self-consistent way. The magnetic field supplies an anisotropic pressure, leading to the braking of the spherical symmetry of the star. In this case, we compute the quadrupole moment of the mass distribution. Next, we perform an estimate of the GW of such objects. Finally, we show that the new recent observation and measurement pulsar white dwarf AR Scorpii, as well other stellar models, are able to generate gravitational wave radiation that lies in the bandwidth of the discussed next generation of space-based GW detectors DECI-hertz interferometer Gravitational wave Observatory (DECIGO) and Big Bang Observer (BBO).