AR Scorpii (AR Sco) is an intriguing binary system that contains both a white and red dwarf. The spin rate of the white dwarf has been observed to slow down with time, analogous to the case of rotation-powered radio pulsars; it has thus been dubbed a ``white dwarf pulsar''. We previously fit the traditional radio pulsar rotating vector model to orbitally-modulated, linearly-polarized optical data (probably synchrotron radiation) from this source, constraining the system geometry and white dwarf mass.
We are now constructing and calibrating
a more sophisticated emission model, solving the particle dynamics from first principles, including a generalized radiation reaction force, and implementing similar techniques to what were used in a pulsar emission code developed by A.K. Harding and collaborators to produce sky maps, light curves and spectra. Here we present first results of the particle pitch-angle and Lorentz-factor evolution, as well as studying the impact of using generalised dynamical equations vs. a super-relativistic approximation.
Additionally, we investigate a magnetic mirror scenario, similar to that of Takata et al. (2017), and show the importance of not being constrained by assumptions of super-relativistic particles with small pitch angles.
Finally, we mention our future plans to calculate the orbitally phase-resolved spin light curves, spectra, and polarisation properties of AR Sco.