Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer
8 affiliations
- 1Norwegian University of Science and Technology
- 2University of Valladolid UVA
- 3Aix Marseille Univ
- 4Universitat Politècnica de Catalunya
- 5Princeton Plasma Physics Laboratory
- 6Northwestern University
- 7NSF-Simons AI Institute for the Sky (SkAI)
- 8University of Toronto
Abstract
Transitional millisecond pulsars (tMSPs) alternate between radio and X-ray pulsar states, and can represent the missing link between rotation- and accretion-powered neutron stars. Their disk state switches stochastically between low and high X-ray modes, both of unknown physical origin and less luminous than low-mass X-ray binaries. To reveal the source of the X-ray emission, we carry out 2D axisymmetric general-relativistic magnetohydrodynamical simulations of the interaction between an accretion disk and a tMSP magnetosphere. For the first time, we postprocess tMSP simulations with a radiative transfer code that incorporates thermal synchrotron, absorption, and Compton scattering processes. By varying the disk density, hence the inflow rate, we explore two disk regimes: one truncated outside and another inside the light cylinder. In the former, most of the X-ray flux comes from the synchrotron emission powered by the wind heating the disk: this “wind” regime could correspond to the high X-ray mode . The latter is the classical propeller regime and lacks this heating. However, the propeller episodically expels the disk, activating the wind heating: a 70%–30% mixture of such propeller and wind regimes reproduces the X-ray spectrum of the low X-ray mode . The excess electromagnetic torque in the propeller regime increases the spin-down rate, averaged over both modes, by a few percent above the disk-free radio pulsar state, in agreement with observations. Overall, the system is more luminous in X-rays when the flow is truncated outside the light cylinder and supports a contribution from wind-induced disk heating in both low and high X-ray modes.
Related
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BibTeX
@article{mignonrisse2026modes,
title = {{Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer}},
author = {Raphaël Mignon-Risse and Manuel Linares and Kyle Parfrey and Alexander Tchekhovskoy and Sean Ressler},
journal = {Astrophys.J.Lett.},
year = {2026},
month = sep,
doi = {10.3847/2041-8213/aeb00c},
eprint = {2607.19113},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05734273v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer
AU - Raphaël Mignon-Risse
AU - Manuel Linares
AU - Kyle Parfrey
AU - Alexander Tchekhovskoy
AU - Sean Ressler
PY - 2026
DA - 2026/09/01
JO - Astrophys.J.Lett.
DO - 10.3847/2041-8213/aeb00c
UR - https://hal.science/hal-05734273v1
AB - Transitional millisecond pulsars (tMSPs) alternate between radio and X-ray pulsar states, and can represent the missing link between rotation- and accretion-powered neutron stars. Their disk state switches stochastically between low and high X-ray modes, both of unknown physical origin and less luminous than low-mass X-ray binaries. To reveal the source of the X-ray emission, we carry out 2D axisymmetric general-relativistic magnetohydrodynamical simulations of the interaction between an accretion disk and a tMSP magnetosphere. For the first time, we postprocess tMSP simulations with a radiative transfer code that incorporates thermal synchrotron, absorption, and Compton scattering processes. By varying the disk density, hence the inflow rate, we explore two disk regimes: one truncated outside and another inside the light cylinder. In the former, most of the X-ray flux comes from the synchrotron emission powered by the wind heating the disk: this “wind” regime could correspond to the high X-ray mode . The latter is the classical propeller regime and lacks this heating. However, the propeller episodically expels the disk, activating the wind heating: a 70%–30% mixture of such propeller and wind regimes reproduces the X-ray spectrum of the low X-ray mode . The excess electromagnetic torque in the propeller regime increases the spin-down rate, averaged over both modes, by a few percent above the disk-free radio pulsar state, in agreement with observations. Overall, the system is more luminous in X-rays when the flow is truncated outside the light cylinder and supports a contribution from wind-induced disk heating in both low and high X-ray modes.
SN - 2041-8205
SN - 2041-8213
ER -