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Main Authors: Zhong, Xinyi, Lai, Xiaoyu
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.15502
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author Zhong, Xinyi
Lai, Xiaoyu
author_facet Zhong, Xinyi
Lai, Xiaoyu
contents Millisecond pulsars (MSPs) are recycled pulsars which have been spun-up due to mass accretion during the phase of mass exchange in binaries. Although the interactions with companion stars play important roles on the spin-up process, the global properties of pulsars determined by the equation of state (EoS), such as mass, radius and the moment of inertia, should also play a role. We investigate the spin-up of MSPs in neutron star (NS) and strangeon star (SS) models, both of which have passed the tests by the existence of high-mass pulsars and the tidal deformability of GW~170817. Combining the spin-up condition and the transferred angular momentum, and taking into account the evolution of magnetic field strength during accretion, we can constrain the spin-period and mass of an MSP. Our results show that the impeding effect of magnetic field on the spin-up of MSPs would be more significant for NSs than for SSs, especially for the ones with low masses. In the low-mass ($M$ below or around about $1.2 M_\odot$) case, an SS can spin faster than an NS of the same mass by accreting the same amount of mass. Finding more low-mass and fully recycled MSPs, with accurate mass-measurement and better constraints on the amount of accreted mass, could help to put more strict constraints on the EoS of pulsars.
format Preprint
id arxiv_https___arxiv_org_abs_2501_15502
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The role of equation of state on the spin-up of millisecond pulsars
Zhong, Xinyi
Lai, Xiaoyu
High Energy Astrophysical Phenomena
Millisecond pulsars (MSPs) are recycled pulsars which have been spun-up due to mass accretion during the phase of mass exchange in binaries. Although the interactions with companion stars play important roles on the spin-up process, the global properties of pulsars determined by the equation of state (EoS), such as mass, radius and the moment of inertia, should also play a role. We investigate the spin-up of MSPs in neutron star (NS) and strangeon star (SS) models, both of which have passed the tests by the existence of high-mass pulsars and the tidal deformability of GW~170817. Combining the spin-up condition and the transferred angular momentum, and taking into account the evolution of magnetic field strength during accretion, we can constrain the spin-period and mass of an MSP. Our results show that the impeding effect of magnetic field on the spin-up of MSPs would be more significant for NSs than for SSs, especially for the ones with low masses. In the low-mass ($M$ below or around about $1.2 M_\odot$) case, an SS can spin faster than an NS of the same mass by accreting the same amount of mass. Finding more low-mass and fully recycled MSPs, with accurate mass-measurement and better constraints on the amount of accreted mass, could help to put more strict constraints on the EoS of pulsars.
title The role of equation of state on the spin-up of millisecond pulsars
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2501.15502