Magnetic field evolution in neutron stars: one-dimensional multi-fluid model

Hoyos, J.; Reisenegger, Andreas; Valdivia, J. A.

doi:10.1051/0004-6361:200809466

Cited by 59 publications

(60 citation statements)

References 27 publications

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“…state after overcoming stable stratification by means of direct and inverse β−decays and ambipolar diffusion acting on timescales shorter than their lifetime (Hoyos et al 2008;Reisenegger 2009;Reisenegger, these Proceedings;Mitchell et al, these Proceedings).…”

Section: Overviewmentioning

confidence: 99%

Magnetohydrodynamic equilibria in barotropic stars

Armaza¹,

Reisenegger²,

Valdivia

et al. 2013

Proc. IAU

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Abstract. Although barotropic matter does not constitute a realistic model for magnetic stars on short timescales, it would be interesting to confirm a recent conjecture that states that magnetized stars with a barotropic equation of state would be dynamically unstable (Reisenegger 2009). In this work we construct a set of barotropic equilibria, which can eventually be tested using a stability criterion. A general description of the ideal MHD equations governing these equilibria is summarized, allowing for both poloidal and toroidal magnetic field components. A new finite-difference numerical code is developed in order to solve the so-called Grad-Shafranov equation describing the equilibrium of these configurations, and some properties of the equilibria obtained are briefly discussed.

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Section: Overviewmentioning

confidence: 99%

Magnetohydrodynamic equilibria in barotropic stars

Armaza¹,

Reisenegger²,

Valdivia

et al. 2013

Proc. IAU

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“…This process has been studied for the first time in the context of neutron star magnetic field decay by Goldreich & Reisenegger (1992). It is a dissipative process that may dominate the evolution of the magnetic field maintained by currents in the core and is another process which is tightly connected to the thermal evolution of neutron stars (Hoyos et al 2008(Hoyos et al , 2010Glampedakis et al 2011). In the pioneering work of Goldreich & Reisenegger (1992), the background neutrons in the core were assumed to be immobile with respect to the with the field co-moving charged particles.…”

Section: The Many Facets Of Magneto -Thermal Interactionsmentioning

confidence: 99%

Magneto–Thermal Evolution of Neutron Stars with Emphasis to Radio Pulsars

Geppert¹

2017

J Astrophys Astron

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The magnetic and thermal evolution of neutron stars is a very complex process with many, also non-linear, interactions. For a decent understanding of neutron star physics, these evolutions cannot be considered isolated. A brief overview is presented, which describes the main magneto -thermal interactions that determine the fate both of isolated neutron stars and accreting ones. Special attention is devoted to the interplay of thermal and magnetic evolution at the polar cap of radio pulsars. There, a strong meridional temperature gradient is maintained over the lifetime of radio pulsars. It may be strong enough to drive thermoelectric magnetic field creation which perpetuate a toroidal magnetic field around the polar cap rim. Such a local field component may amplify and curve the poloidal surface field at the cap, forming a strong and small scale magnetic field there as required for the radio emission of pulsars.Key words: stars: neutron -stars: magnetic fields -pulsars: general -stars: interiors PREFACEWhen I started to try to understand some aspects of neutron star physics, one of the first papers I read was Srinivasan & van den Heuvel (1982) about the evolution of millisecond pulsars. Then the connection between the (at that time in optical light) invisible pulsars and the fascinating manifestations of supernova remnants (Srinivasan et al. 1984) increased my interest in this branch of astrophysics. The observation of millisecond pulsars in the early eighties was a challenge, which was met by Prof. Srinivasan and his colleagues (see e.g. Bhattacharya & Srinivasan (1986);Srinivasan (1989)). Later the pioneering work of Srinivasan et al. (1990) triggered my interest to understand how the very long-lived core magnetic field is affected by the rotational history of neutron stars and how the evolutions of core and crustal field are coupled to each other. Meanwhile Prof. Srinivasan enriched our knowledge about neutron stars by many contributions, among others about their evolution in accreting binary systems, about the recycling of old pulsars to millisecond pulsars, about the supernova remnants and pulsar wind nebulae which are results of neutron star births, about the use of radiotelescope for pulsar observations and about many other topics. As far as I can see being a far distant observer, Prof. Srinivasan succeeded also in the formation of a group of excellent and worldwide renown Indian scientists working in the field of neutron star physics.⋆ E-mail:ulrich.geppert@dlr.deMay be there exists a not yet discovered age-relativistic effect that makes the time running faster when seen by an aging person. It seems to be this effect that made me surprised to recognize that Prof. Srinivasan celebrates already his 75th birthday. This special issue is a good opportunity to esteem his life-work and I am happy that I can contribute to it. THE MANY FACETS OF MAGNETO -THERMAL INTERACTIONS

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“…At high temperatures (corresponding to the "strong-coupling" regime in the onedimensional simulations of Hoyos et al 2008Hoyos et al , 2010, the main change is that, over long enough times, neutrons and charged particles can convert into each other through beta decays, eventually establishing a chemical equilibrium controlled by only one variable, e.g., the local pressure or density. This means that, in its secular evolution, the fluid will behave as if it were barotropic, with P 1 and ρ 1 in eq.…”

Section: Dissipative Processes and Field Evolutionmentioning

confidence: 99%

“…At lower temperatures (the "weak-coupling" regime of Hoyos et al 2008Hoyos et al , 2010, the fluid becomes more and more degenerate, reducing the phase space for interactions and thus the conversion rates between neutrons and charged particles, but also the drag forces between them, so a two-fluid model becomes more applicable. The magnetic field will be coupled only to the charged particles, and it will force them to move relative to the neutrons in a process called ambipolar diffusion (Pethick 1991;.…”

Section: Dissipative Processes and Field Evolutionmentioning

confidence: 99%

Hydromagnetic Equilibria and their Evolution in Neutron Stars

Reisenegger¹

2013

Proc. IAU

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Abstract. The strongest known magnetic fields are found in neutron stars. I briefly discuss how they are inferred from observations, as well as the evidence for their time-evolution. I go on to show how these extremely strong fields are actually weak in terms of their effects on the stellar structure. This is also the case for magnetic stars on the upper main sequence and magnetic white dwarfs, which have similar total magnetic fluxes, perhaps pointing to an evolutionary connection. I suggest that a stable hydromagnetic equilibrium (containing a poloidal and a toroidal field component) could be established soon after the birth of the neutron star, aided by the strong compositional stratification of neutron star matter, and this state is slowly eroded by non-ideal magnetohydrodynamic processes such as beta decays and ambipolar diffusion in the core of the star and Hall drift and breaking of the solid in its crust. Over sufficiently long time scales, the fluid in the neutron star core will behave as if it were barotropic, because, depending on temperature and magnetic field strength, beta decays will keep adjusting the composition to the chemical equilibrium state, or ambipolar diffusion will decouple the charged component from the neutrons. Therefore, the still open question regarding stable hydromagnetic equilibria in barotropic fluids will become relevant for the evolution, at least for magnetar fields, which are likely too strong to be stabilized by the solid crust.

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Magnetic field evolution in neutron stars: one-dimensional multi-fluid model

Cited by 59 publications

References 27 publications

Magnetohydrodynamic equilibria in barotropic stars

Magnetohydrodynamic equilibria in barotropic stars

Magneto–Thermal Evolution of Neutron Stars with Emphasis to Radio Pulsars

Hydromagnetic Equilibria and their Evolution in Neutron Stars

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