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Main Authors: Ertugrul, Fatmanur, Gencali, Ali Arda, Ertan, Unal, Niang, Ndiogou
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.16670
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author Ertugrul, Fatmanur
Gencali, Ali Arda
Ertan, Unal
Niang, Ndiogou
author_facet Ertugrul, Fatmanur
Gencali, Ali Arda
Ertan, Unal
Niang, Ndiogou
contents Accreting millisecond X-ray pulsars (AMXPs) are transient X-ray sources likely to be in the final evolutionary phases of low-mass X-ray binaries (LMXBs). In this work, we have investigated the torque and X-ray luminosity variations of five AMXPs during outburst and quiescence, using a model previously employed to explain some typical behaviours of LMXBs. Most of these systems spin up in the outburst state and spin down in quiescence, while they slow down on the long term. We have obtained reasonable results with the model in agreement with these observations. We have found that the torques produced by the disc-magnetosphere interaction, the magnetic dipole radiation, and the mass accretion are compatible with the X-ray luminosity and rotational properties of the sources in their outburst and quiescent states, and during the resultant long-term evolution. Nevertheless, our results are not sufficient to rule out the spin-down contribution of the gravitational radiation torques due to significant timing noise and uncertainties about the bolometric corrections for X-ray luminosity during the outbursts of some sources.
format Preprint
id arxiv_https___arxiv_org_abs_2605_16670
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Torques Acting on Accreting Millisecond X-Ray Pulsars in the Outburst and Quiescent States, and During the Long-Term Evolution
Ertugrul, Fatmanur
Gencali, Ali Arda
Ertan, Unal
Niang, Ndiogou
High Energy Astrophysical Phenomena
Accreting millisecond X-ray pulsars (AMXPs) are transient X-ray sources likely to be in the final evolutionary phases of low-mass X-ray binaries (LMXBs). In this work, we have investigated the torque and X-ray luminosity variations of five AMXPs during outburst and quiescence, using a model previously employed to explain some typical behaviours of LMXBs. Most of these systems spin up in the outburst state and spin down in quiescence, while they slow down on the long term. We have obtained reasonable results with the model in agreement with these observations. We have found that the torques produced by the disc-magnetosphere interaction, the magnetic dipole radiation, and the mass accretion are compatible with the X-ray luminosity and rotational properties of the sources in their outburst and quiescent states, and during the resultant long-term evolution. Nevertheless, our results are not sufficient to rule out the spin-down contribution of the gravitational radiation torques due to significant timing noise and uncertainties about the bolometric corrections for X-ray luminosity during the outbursts of some sources.
title The Torques Acting on Accreting Millisecond X-Ray Pulsars in the Outburst and Quiescent States, and During the Long-Term Evolution
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.16670