Magnetic field evolution time-scales in superconducting neutron stars

Gusakov, M. E.; Kantor, E. M.; Ofengeim, D. D.

doi:10.1093/mnras/staa3160

Cited by 24 publications

(28 citation statements)

References 64 publications

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“…Recently, Gusakov et al (2020) suggested that an episode of magnetic field decay at ages ∼10 5 yrs can be explained by field evolution in a NS core. This is an interesting and intriguing possibility.…”

Section: New Results and Comparison With Our Early Studiesmentioning

confidence: 99%

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Magnetic field decay in young radio pulsars

Igoshev

Попов

2021

Astron Nachr

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The role of magnetic field decay in normal radio pulsars is still debated. In this paper, we present results which demonstrate that an episode of magnetic field decay in hot young neutron stars can explain anomalous values of braking indices recently measured for more than a dozen of sources. It is enough to have few tens of per cent of such hot neutron stars in the total population to explain observables. Relatively rapid decay operates at ages ≲ few ×100 kyrs with a characteristic timescale of a similar value. We speculate that this decay can be related to electron scattering off phonons in neutron star crusts. This type of decay saturates as a neutron star cools down. Later on, a much slower decay due to crustal impurities dominates. Finally, we demonstrate that this result is in agreement with our early studies.

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Section: New Results and Comparison With Our Early Studiesmentioning

confidence: 99%

“…Recently, Gusakov et al (2020) suggested that an episode of magnetic field decay at ages ∼10 5 yrs can be 2 Decay might be much slower for very massive NSs with M ≳ 1.8 M ⊙ -for the chosen equation of state,-with efficient direct URCA cooling, in these objects the phonon resistivity becomes unimportant very rapidly.…”

Section: F I G U R Ementioning

confidence: 99%

Magnetic field decay in young radio pulsars

Igoshev

Попов

2021

Astron Nachr

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“…Recently, Gusakov et al (2020) modeled the ambipolar diffusion in the NS core. They noticed that magnetic field in the core could evolve significantly on timescales of NS cooling, i.e., 10 4 -10 6 yr , 2020.…”

Section: Discussionmentioning

confidence: 99%

“…Physically this corresponds to a scenario in which the field is expelled from the core before the crust solidifies. In reality, the core might still contain some magnetic field, although the timescale on which the core field evolves is uncertain; see, e.g., Gusakov et al (2020). For the magnetic field at the outer boundary we use vacuum boundary conditions, i.e., we assume that ∇ × B = 0 in the region outside the star.…”

Section: Boundary and Initial Conditionsmentioning

confidence: 99%

3D Magnetothermal Simulations of Tangled Crustal Magnetic Field in Central Compact Objects

Igoshev

Gourgouliatos

Hollerbach

et al. 2021

ApJ

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Central compact objects (CCOs) are young neutron stars emitting thermal X-rays with bolometric luminosities L X in the range of 10 32 -10 34 erg s −1 . Gourgouliatos, Hollerbach, and Igoshev recently suggested that peculiar emission properties of CCOs can be explained by tangled magnetic field configurations formed in a stochastic dynamo during the proto-neutron star stage. In this case the magnetic field consists of multiple small-scale components with negligible contribution of global dipolar field. We study numerically three-dimensional magnetothermal evolution of tangled crustal magnetic fields in neutron stars. We find that all configurations produce complicated surface thermal patterns that consist of multiple small hot regions located at significant separations from each other. The configurations with initial magnetic energy of (2.5-10) × 10 47 erg have temperatures of hot regions that reach ≈ 0.2 keV, to be compared with the bulk temperature of ≈ 0.1 keV in our simulations with no cooling. A factor of two in temperature is also seen in observations of CCOs. The hot spots produce periodic modulations in light curve with typical amplitudes of 9%-11%. Therefore, the tangled magnetic field configuration can explain thermal emission properties of some CCOs.

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“…When the temperature drops below ≈10 9 K in the core, the protons will be superconducting and the neutrons superfluid (Haskell & Sedrakian 2018), which will have a significant effect on the evolution of the field in the standard pulsar population (Ofengeim & Gusakov 2018;Gusakov et al 2017b;Gusakov et al 2020). Superconductivity, in particular, affect the magnetic field, as if it is of type II, as theoretical models suggest, the field will be confined to flux tubes, which can also interact with superfluid neutron vortices (see Haskell & Sedrakian 2018 for a review).…”

Section: Introductionmentioning

confidence: 99%

The impact of superconductivity and the Hall effect in models of magnetised neutron stars

Sur

Haskell

2021

Publ. Astron. Soc. Aust.

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Equilibrium configurations of the internal magnetic field of a pulsar play a key role in modelling astrophysical phenomena from glitches to gravitational wave emission. In this paper, we present a numerical scheme for solving the Grad–Shafranov equation and calculating equilibrium configurations of pulsars, accounting for superconductivity in the core of the neutron star, and for the Hall effect in the crust of the star. Our numerical code uses a finite difference method in which the source term appearing in the Grad–Shafranov equation, which is used to model the magnetic equilibrium is non-linear. We obtain solutions by linearising the source and applying an under-relaxation scheme at each step of computation to improve the solver’s convergence. We have developed our code in both C++ and Python, and our numerical algorithm can further be adapted to solve any non-linear PDEs appearing in other areas of computational astrophysics. We produce mixed toroidal–poloidal field configurations, and extend the portion of parameter space that can be investigated with respect to previous studies. We find that in even in the more extreme cases, the magnetic energy in the toroidal component does not exceed approximately 5% of the total. We also find that if the core of the star is superconducting, the toroidal component is entirely confined to the crust of the star, which has important implications for pulsar glitch models which rely on the presence of a strong toroidal field region in the core of the star, where superfluid vortices pin to superconducting fluxtubes.

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Magnetic field evolution time-scales in superconducting neutron stars

Cited by 24 publications

References 64 publications

Magnetic field decay in young radio pulsars

Magnetic field decay in young radio pulsars

3D Magnetothermal Simulations of Tangled Crustal Magnetic Field in Central Compact Objects

The impact of superconductivity and the Hall effect in models of magnetised neutron stars

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