A reevaluation of the proposed spin-down of the white dwarf pulsar in AR Scorpii

TL;DR

This study presents two years of high-speed optical observations of AR Scorpii, revealing stable modulation amplitudes but inconsistent spin-down behavior with previous models, highlighting the need for extended monitoring.

Contribution

It provides new observational data challenging existing spin-down models of the white dwarf pulsar in AR Scorpii.

Findings

Stable amplitudes of modulations over two years

Inconsistency with previously published spin-down ephemeris

Data compatible with a constant spin period

Abstract

We present high-speed optical photometric observations, spanning ~2 years, of the recently-discovered white dwarf pulsar AR Scorpii. The amplitudes of the orbital, spin and beat modulations appear to be remarkably stable and repeatable over the time span of our observations. It has been suggested that the polarized and non-polarized emission from AR Scorpii is powered by the spin-down of the white dwarf. However, we find that our new data is inconsistent with the published spin-down ephemeris. Whilst our data is consistent with a constant spin period further observations over an extended time-base are required in order to ascertain the true spin-evolution of the white dwarf.