Efficacy of magnetically driven temperature-dependent plastic flows in exciting the magnetosphere of CXOU J164710.2-455216

Kwang-Hua, Chu W.

doi:10.1007/s10509-018-3407-x

Cited by 5 publications

(2 citation statements)

References 48 publications

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“…Note that a calculation of this quantity from theoretical grounds has been attempted by Kwang-Hua (2018), and is orders of magnitude lower than the above. If this were correct, plastic evolution would be so fast that the crust would be immediately returned to its elastic regime, and it seems doubtful that any large-scale gradual magnetospheric twisting could occur.…”

Section: Materials Properties Of the Crustmentioning

confidence: 91%

Magnetic-field evolution in a plastically failing neutron-star crust

Lander

Gourgouliatos

2019

Monthly Notices of the Royal Astronomical Society

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Under normal conditions in a neutron-star crust, ions are locked in place in the crustal lattice and only electrons are mobile, and magnetic-field evolution is thus directly related to the electron velocity. The evolution, however, builds magnetic stresses that can become sufficiently large for the crust to exceed its elastic limit, and to flow plastically. We consider the nature of this plastic flow and the back-reaction on the crustal magnetic field evolution. We formulate a plane-parallel model for the local failure, showing that surface motions are inevitable once the crust yields, in the absence of extra dissipative mechanisms. We perform numerical evolutions of the crustal magnetic field under the joint effect of Hall drift and Ohmic decay, tracking the build-up of magnetic stresses, and diagnosing crustal failure with the von Mises criterion. Beyond this point we solve for the coupled evolution of the plastic velocity and magnetic field. Our results suggest that to have a coexistence of a magnetar corona with small-scale magnetic features, the viscosity of the plastic flow must be roughly 10 36 − 10 37 g cm −1 s −1 . We find significant motion at the surface at a rate of 10 − 100 centimetres per year, and that the localised magnetic field is weaker than in evolutions without plastic flow. We discuss astrophysical implications, and how our local simulations could be used to build a global model of field evolution in the neutron-star crust.

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Section: Materials Properties Of the Crustmentioning

confidence: 91%

Magnetic-field evolution in a plastically failing neutron-star crust

Lander

Gourgouliatos

2019

Monthly Notices of the Royal Astronomical Society

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“…For these objects it could be useful to take into accounts also the long-time evolution of elastic layers due to a non-null viscosity. However, at the present time, the viscosity ν of NSs' crust is essentially unknown, even if in the last years some first estimations have appeared(Kwang-Hua 2018;Lander & Gourgouliatos 2019). The inclusion also of this parameter in a consistent model…”

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confidence: 89%

Starquakes in millisecond pulsars and gravitational waves emission

Giliberti,

Cambiotti

2021

Preprint

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So far, only transient Gravitational waves (GWs) produced by catastrophic events of extra-galactic origin have been detected. However, it is generally believed that there should be also continuous sources of GWs within our galaxy, such as accreting neutron stars (NSs). In fact, in accreting NSs, centrifugal forces can be so strong to break the neutron star crust (causing a starquake), thus producing a quadrupole moment responsible for the continuous emission of GWs. At equilibrium, the angular momentum gained by accretion and lost via GWs emission should balance each other, stopping the stellar spin-up.We hereinafter investigate the above physical picture within the framework of a Newtonian model describing compressible, non-magnetized and self-gravitating NSs. In particular, we calculate the rotational frequency need to break the stellar crust of an accreting pulsar and we estimate the upper limit for the ellipticity due to this event. Depending on the equation of state (EoS) and on the mass of the star, we calculated that the starquake-induced ellipticity ranges from 10 −9 to 10 −5 . The corresponding equilibrium frequency that we find is in good agreement with observations and, for all the scenarios, it is below the observational limit frequency of 716.36 Hz. Finally, we also discuss possible observational constraints on the ellipticity upper limit of accreting pulsars.

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Starquakes in millisecond pulsars and gravitational waves emission

Giliberti

Cambiotti

2022

Monthly Notices of the Royal Astronomical Society

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So far, only transient Gravitational waves (GWs) produced by catastrophic events of extra-galactic origin have been detected. However, it is generally believed that there should be also continuous sources of GWs within our galaxy, such as accreting neutron stars (NSs), that could in principle be detected in the next near future. In fact, in these objects, centrifugal forces can be so strong to break the neutron star crust (causing a starquake), thus producing a quadrupole moment responsible for the continuous emission of GWs. At equilibrium, the angular momentum gained by accretion and the one lost via GWs emission should balance each other, stopping the stellar spin-up. We hereinafter investigate the above physical picture within the framework of a Newtonian model describing compressible, non-magnetized and self-gravitating NSs. In particular, we calculate the rotational frequency need to break the stellar crust of an accreting pulsar and we estimate the upper limit for the ellipticity due to this event. We find that the maximum starquake-induced ellipticity ranges from 10−9 to 10−5, depending on the stellar mass and its equation of state. The corresponding equilibrium frequency that we calculate is in good agreement with observations and, for all the scenarios, it is below the higher NS frequency observed of 716.36 Hz. Finally, we also discuss possible observational constraints on the ellipticity upper limit of accreting pulsars.

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Efficacy of magnetically driven temperature-dependent plastic flows in exciting the magnetosphere of CXOU J164710.2-455216

Cited by 5 publications

References 48 publications

Magnetic-field evolution in a plastically failing neutron-star crust

Magnetic-field evolution in a plastically failing neutron-star crust

Starquakes in millisecond pulsars and gravitational waves emission

Starquakes in millisecond pulsars and gravitational waves emission

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