White Dwarf Pulsars: an emerging class of compact binaries
Abstract
I summarise the expanding class of white dwarf pulsars for which the prototype, AR Scorpii, was only discovered in 2016. At the time of this meeting, two further systems had been found (eRASSU J191213.9-441044 and SDSS J230641.47+244055.8). These are thought to be detached (or nearly detached) white-dwarf--red-dwarf binaries, where the white dwarf's magnetic field interacts with the M-star's corona, resulting in the capture and acceleration of electrons to relativistic velocities in the magnetosphere. This gives rise to non-thermal synchrotron emission across the electromagnetic spectrum. The first discovered, and brightest, system, AR Sco (which is the focus of this paper), shows a white dwarf spin-down consistent with magnetic dipole emission in a strongly magnetic white dwarf. The polarisation properties of the two systems for which polarimetry has been obtained (AR Sco and eRASSU J191213.9-441044) show spin-modulated polarisation, primarily linear, which remarkably reaches 40% in AR Sco. Furthermore, the Stokes Q and U parameters vary in the same manner as the optical polarisation of the Crab pulsar, consistent with a rotating magnetic dipole. These systems are intriguing in that each one seems to show different behaviours (e.g. pulse profiles and light-curve properties), presumably mainly due to different viewing aspect angles. It has recently been postulated that these systems represent a short-lived phase of binary evolution linking asynchronously rotating intermediate polars and synchronous polars.
Related
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BibTeX
@misc{buckley2026white,
title = {{White Dwarf Pulsars: an emerging class of compact binaries}},
author = {David A. H. Buckley},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27543},
eprint = {2609.27543},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27543},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - White Dwarf Pulsars: an emerging class of compact binaries
AU - David A. H. Buckley
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27543
UR - https://arxiv.org/abs/2609.27543
AB - I summarise the expanding class of white dwarf pulsars for which the prototype, AR Scorpii, was only discovered in 2016. At the time of this meeting, two further systems had been found (eRASSU J191213.9-441044 and SDSS J230641.47+244055.8). These are thought to be detached (or nearly detached) white-dwarf--red-dwarf binaries, where the white dwarf's magnetic field interacts with the M-star's corona, resulting in the capture and acceleration of electrons to relativistic velocities in the magnetosphere. This gives rise to non-thermal synchrotron emission across the electromagnetic spectrum. The first discovered, and brightest, system, AR Sco (which is the focus of this paper), shows a white dwarf spin-down consistent with magnetic dipole emission in a strongly magnetic white dwarf. The polarisation properties of the two systems for which polarimetry has been obtained (AR Sco and eRASSU J191213.9-441044) show spin-modulated polarisation, primarily linear, which remarkably reaches 40% in AR Sco. Furthermore, the Stokes Q and U parameters vary in the same manner as the optical polarisation of the Crab pulsar, consistent with a rotating magnetic dipole. These systems are intriguing in that each one seems to show different behaviours (e.g. pulse profiles and light-curve properties), presumably mainly due to different viewing aspect angles. It has recently been postulated that these systems represent a short-lived phase of binary evolution linking asynchronously rotating intermediate polars and synchronous polars.
ER -