Modelling neutron star magnetic fields

Gourgouliatos, Konstantinos N.; Hollerbach, Rainer; Archibald, R. F.

doi:10.1093/astrogeo/aty235

Cited by 11 publications

(11 citation statements)

References 49 publications

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“…In response to challenges based on observational data, many models with evolving magnetic field (e.g., see reviews and references in Cumming et al 2004;Gourgouliatos et al 2018;Pons & Viganò 2019) and angle (Philippov et al 2014;Dall'Osso & Perna 2017) were developed, as well as several modifications for the equation describing rotational energy losses were proposed (e.g., Beskin et al 1993; Beskin 2018 and references therein). These scenarios ★ E-mail: ignotur@gmail.com predict different timing evolution for single radio pulsars.…”

Section: Introductionmentioning

confidence: 99%

Braking indices of young radio pulsars: theoretical perspective

Igoshev

Попов

2020

Monthly Notices of the Royal Astronomical Society

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Recently, Parthsarathy et al. analysed long-term timing observations of 85 young radio pulsars. They found that 15 objects have absolute values of braking indices ranging ∼10 − 3000, far from the classical value n = 3. They also noted a mild correlation between measured value of n and characteristic age of a radio pulsar. In this article we systematically analyse possible physical origin of large braking indices. We find that a small fraction of these measurements could be caused by gravitational acceleration from an unseen ultra-wide companion of a pulsar or by precession. Remaining braking indices cannot be explained neither by pulsar obliquity angle evolution, nor by complex high-order multipole structure of the poloidal magnetic field. The most plausible explanation is a decay of the poloidal dipole magnetic field which operates on a time scale ∼104 − 105 years in some young objects, but has significantly longer time scale in other radio pulsars. This decay can explain both amplitude of measured n and some correlation between n and characteristic age. The decay can be caused by either enhanced crystal impurities in the crust of some isolated radio pulsars, or more likely, by enhanced resistivity related to electron scattering off phonons due to slow cooling of low-mass neutron stars. If this effect is indeed the main cause of the rapid magnetic field decay manifesting as large braking indices, we predict that pulsars with large braking indices are hotter in comparison to those with n ≈ 3.

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Section: Introductionmentioning

confidence: 99%

Braking indices of young radio pulsars: theoretical perspective

Igoshev

Попов

2020

Monthly Notices of the Royal Astronomical Society

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“…That is, the spectra quickly evolve to look like typical turbulent spectra, but if one examines the field structures in physical space, one finds that the evolution seems to saturate after a few Hall timescales, and the magnetic field hardly changes thereafter. This effect was noted in periodic-box geometry by [59,60], and was later also referred to as 'frozen turbulence' [70].…”

Section: Hall Evolutionmentioning

confidence: 91%

Evolution of Neutron Star Magnetic Fields

2021

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Neutron stars are natural physical laboratories allowing us to study a plethora of phenomena in extreme conditions. In particular, these compact objects can have very strong magnetic fields with non-trivial origin and evolution. In many respects, its magnetic field determines the appearance of a neutron star. Thus, understanding the field properties is important for the interpretation of observational data. Complementing this, observations of diverse kinds of neutron stars enable us to probe parameters of electro-dynamical processes at scales unavailable in terrestrial laboratories. In this review, we first briefly describe theoretical models of the formation and evolution of the magnetic field of neutron stars, paying special attention to field decay processes. Then, we present important observational results related to the field properties of different types of compact objects: magnetars, cooling neutron stars, radio pulsars, and sources in binary systems. After that, we discuss which observations can shed light on the obscure characteristics of neutron star magnetic fields and their behaviour. We end the review with a subjective list of open problems.

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“…Hall evolution is not a dissipative process, it is related to changes in the magnetic field topology (Gourgouliatos et al 2018). The Hall time scale depends on the magnetic field of a NS as (Cumming et al 2004):…”

Section: Magnetic Field Decaymentioning

confidence: 99%

τ_{Hall} = \frac{4 π n_{normale} {italiceL}^{2}}{{cB}_{p}},

where c is the speed of light, e is the elementary charge, B p is the poloidal dipolar magnetic field at the pole, n e is the electron number density, and L is length scale related to electric currents structure in the crust.…”

Section: Magnetic Field Decaymentioning

confidence: 99%

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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Modelling neutron star magnetic fields

Cited by 11 publications

References 49 publications

Braking indices of young radio pulsars: theoretical perspective

Braking indices of young radio pulsars: theoretical perspective

Evolution of Neutron Star Magnetic Fields

Magnetic field decay in young radio pulsars

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