Study for curvature radiation and magnetic pair creation process on polar-cap region of magnetic white dwarf
Abstract
Rapidly rotating, strongly magnetized white dwarfs (WDs) have been proposed as potential sites of rotation-powered activity analogous to that of a neutron star pulsar. In this study, we investigate particle acceleration, radiation processes, pair creation and resulting synchrotron radiation in the polar cap acceleration region. Within the framework of the space-charge-limited flow model, we examine how these processes depend on the spin period and surface magnetic field using both one-dimensional numerical calculations and analytical estimates. To explore the impact of the magnetic field geometry on the accelerating process, we consider both a pure dipole field and a combination of dipole and quadrupole fields. The inclusion of a quadrupole component reduces the curvature radius of the magnetic field lines, and significantly enhances the accelerating field, leading to more efficient radiation and pair creation processes. Using this framework, we evaluate the WD death line with a more consistent treatment of the relevant physical processes than the previous studies. We find that the pair creation process can occur for spin periods P≲100~s, when the dipole field strength B*,d≲1010~G, indicating that pair creation is difficult to sustain in currently known magnetic WDs. We discuss the implications of our model for rotation-powered activity in rapidly spinning isolated magnetic WDs and for the possible WD interpretation of long-period radio transients.
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BibTeX
@misc{wang2026study,
title = {{Study for curvature radiation and magnetic pair creation process on polar-cap region of magnetic white dwarf}},
author = {Bingyan Wang and Jumpei Takata},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.25806},
eprint = {2606.25806},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.25806},
note = {CC0},
}
RIS
TY - UNPB
TI - Study for curvature radiation and magnetic pair creation process on polar-cap region of magnetic white dwarf
AU - Bingyan Wang
AU - Jumpei Takata
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2606.25806
UR - https://arxiv.org/abs/2606.25806
AB - Rapidly rotating, strongly magnetized white dwarfs (WDs) have been proposed as potential sites of rotation-powered activity analogous to that of a neutron star pulsar. In this study, we investigate particle acceleration, radiation processes, pair creation and resulting synchrotron radiation in the polar cap acceleration region. Within the framework of the space-charge-limited flow model, we examine how these processes depend on the spin period and surface magnetic field using both one-dimensional numerical calculations and analytical estimates. To explore the impact of the magnetic field geometry on the accelerating process, we consider both a pure dipole field and a combination of dipole and quadrupole fields. The inclusion of a quadrupole component reduces the curvature radius of the magnetic field lines, and significantly enhances the accelerating field, leading to more efficient radiation and pair creation processes. Using this framework, we evaluate the WD death line with a more consistent treatment of the relevant physical processes than the previous studies. We find that the pair creation process can occur for spin periods P≲100~s, when the dipole field strength B_*,d≲10^10~G, indicating that pair creation is difficult to sustain in currently known magnetic WDs. We discuss the implications of our model for rotation-powered activity in rapidly spinning isolated magnetic WDs and for the possible WD interpretation of long-period radio transients.
ER -