scholarly journals Vortex pinning in the superfluid core of relativistic neutron stars

2021 ◽  
Vol 503 (1) ◽  
pp. 1407-1417
Author(s):  
Aurélien Sourie ◽  
Nicolas Chamel
Keyword(s):  
Neutron Stars ◽  
Outer Core ◽  
Vortex Pinning ◽  
Global Dynamics ◽  
Mutual Friction ◽  
Dynamical Equations ◽  
General Relativistic ◽  
Superfluid Core ◽  
Relativistic Framework

ABSTRACT Our recent Newtonian treatment of the smooth-averaged mutual-friction force acting on the neutron superfluid and locally induced by the pinning of quantized neutron vortices to proton fluxoids in the outer core of superfluid neutron stars is here adapted to the general-relativistic framework. We show how the local non-relativistic motion of individual vortices can be matched to the global dynamics of the star using the fully 4D covariant Newtonian formalism of Carter & Chamel. We derive all the necessary dynamical equations for carrying out realistic simulations of superfluid rotating neutron stars in full general relativity, as required for the interpretation of pulsar frequency glitches. The role of vortex pinning on the global dynamics appears to be non-trivial.

scholarly journals Vortex pinning in the superfluid core of neutron stars and the rise of pulsar glitches

2020 ◽  
Vol 493 (1) ◽  
pp. L98-L102 ◽  
Author(s):  
Aurélien Sourie ◽  
Nicolas Chamel
Keyword(s):  
Neutron Stars ◽  
Early Stage ◽  
Vortex Pinning ◽  
Global Dynamics ◽  
Free Precession ◽  
Mode Instability ◽  
The Core ◽  
Superfluid Core ◽  
Superfluid Vortices ◽  
Key Parameter

ABSTRACT Timing of the Crab and Vela pulsars has recently revealed very peculiar evolutions of their spin frequency during the early stage of a glitch. We show that these differences can be interpreted from the interactions between neutron superfluid vortices and proton fluxoids in the core of these neutron stars. In particular, pinning of individual vortices to fluxoids is found to have a dramatic impact on the mutual friction between the neutron superfluid and the rest of the star. The number of fluxoids attached to vortices turns out to be a key parameter governing the global dynamics of the star. These results may have implications for the interpretation of other astrophysical phenomena such as pulsar-free precession or the r-mode instability.

QUASI-STATIONARY ELECTROMAGNETIC EFFECTS IN CONDUCTORS AND SUPERCONDUCTORS IN SCHWARZSCHILD SPACE–TIME

2005 ◽  
Vol 14 (05) ◽  
pp. 817-835 ◽  
Author(s):  
B. J. AHMEDOV ◽  
F. J. FATTOYEV
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Neutron Stars ◽  
Penetration Depth ◽  
Skin Effect ◽  
Outer Core ◽  
Point Of View ◽  
Time Dependent ◽  
General Relativistic ◽  
Stationary Gravitational Field

The general principles needed to compute the effect of a stationary gravitational field on the quasistationary electromagnetic phenomena in normal conductors and superconductors are formulated from general relativistic point of view. Generalization of the skin effect, that is the general relativistic modification of the penetration depth (of the time-dependent magnetic field in the conductor) due to its relativistic coupling to the gravitational field is obtained. The effect of the gravitational field on the penetration and coherence depths in superconductors is also studied. As an illustration of the foregoing general results, we discuss their application to superconducting systems in the outer core of neutron stars. The relevance of these effects to electrodynamics of magnetized neutron stars has been shown.

COVARIANT ANALYSIS OF NEWTONIAN MULTI-FLUID MODELS FOR NEUTRON STARS III: TRANSVECTIVE, VISCOUS, AND SUPERFLUID DRAG DISSIPATION

2005 ◽  
Vol 14 (05) ◽  
pp. 749-774 ◽  
Author(s):  
BRANDON CARTER ◽  
NICOLAS CHAMEL
Keyword(s):  
Neutron Stars ◽  
Variational Formulation ◽  
Meridional Circulation ◽  
Traditional Approach ◽  
Vortex Pinning ◽  
Mutual Friction ◽  
Fluid Models ◽  
Stress Energy ◽  
Time Decomposition

As a follow up to papers dealing firstly with a convective variational formulation in a Milne–Cartan framework for non-dissipative multi-fluid models, and secondly with various ensuing stress energy conservation laws and generalized virial theorems, this work continues a series showing how analytical procedures developed in the context of General Relativity can be usefully adapted for implementation in a purely Newtonian framework where they provide physical insights that are not so easy to obtain by the traditional approach based on a 3+1 space time decomposition. The present paper describes the 4-dimensionally covariant treatment of various dissipative mechanisms, including viscosity in non-superfluid constituents, superfluid vortex drag, ordinary resistivity (mutual friction) between relatively moving non-superfluid constituents, and the transvective dissipation that occurs when matter is transformed from one constituent to another due to chemical disequilibrium such as may be produced by meridional circulation in neutron stars. The corresponding non-dissipative limit cases of vortex pinning, convection and chemical equilibrium are also considered.

scholarly journals The role of mass, equation of state, and superfluid reservoir in large pulsar glitches

2020 ◽  
Vol 492 (4) ◽  
pp. 4837-4846 ◽  
Author(s):  
A Montoli ◽  
M Antonelli ◽  
P M Pizzochero
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Small Region ◽  
Outer Core ◽  
Rotational Dynamics ◽  
Internal Layers ◽  
S Wave ◽  
Average Activity

ABSTRACT Observations of pulsar glitches may provide insights on the internal physics of neutron stars and recent studies show how it is in principle possible to constrain pulsar masses with timing observations. The reliability of these estimates depends on the current uncertainties about the structure of neutron stars and on our ability to model the dynamics of the superfluid neutrons in the internal layers. We assume a simplified model for the rotational dynamics of a neutron star and estimate an upper bound to the mass of 25 pulsars from their largest glitch and average activity: the aim is to understand to which extent the mass constraints are sensitive to the choice of the unknown structural properties of neutron stars, like the extension of the superfluid region and the equation of state. Reasonable values, within the range measured for neutron star masses, are obtained only if the superfluid domain extends for at least a small region inside the outer core, which is compatible with calculations of the neutron S-wave pairing gap. Moreover, the mass constraints stabilize when the superfluid domain extends to densities over nuclear saturation, irrespective of the equation of state tested.

scholarly journals GENERAL RELATIVISTIC EQUILIBRIUM MODELS OF MAGNETIZED NEUTRON STARS

2014 ◽  
Vol 28 ◽  
pp. 1460202 ◽  
Author(s):  
A. G. PILI ◽  
N. BUCCIANTINI ◽  
L. DEL ZANNA
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Compact Objects ◽  
Equilibrium Models ◽  
Global Properties ◽  
Different Types ◽  
General Relativistic ◽  
Grmhd Equations ◽  
The Magnetic Field

Magnetic fields play a crucial role in many astrophysical scenarios and, in particular, are of paramount importance in the emission mechanism and evolution of Neutron Stars (NSs). To understand the role of the magnetic field in compact objects it is important to obtain, as a first step, accurate equilibrium models for magnetized NSs. Using the conformally flat approximation we solve the Einstein's equations together with the GRMHD equations in the case of a static axisymmetric NS taking into account different types of magnetic configuration. This allows us to investigate the effect of the magnetic field on global properties of NSs such as their deformation.

scholarly journals Force on a neutron quantized vortex pinned to proton fluxoids in the superfluid core of cold neutron stars

2020 ◽  
Vol 493 (1) ◽  
pp. 382-389 ◽  
Author(s):  
Aurélien Sourie ◽  
Nicolas Chamel
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
General Expression ◽  
Vortex Dynamics ◽  
Cold Neutron ◽  
Vortex Pinning ◽  
Quantized Vortices ◽  
Single Vortex ◽  
The Core ◽  
Superfluid Core

ABSTRACT The superfluid and superconducting core of a cold rotating neutron star (NS) is expected to be threaded by a tremendous number of neutron quantized vortices and proton fluxoids. Their interactions are unavoidable and may have important astrophysical implications. In this paper, the various contributions to the force acting on a single vortex to which fluxoids are pinned are clarified. The general expression of the force is derived by applying the variational multifluid formalism developed by Carter and collaborators. Pinning to fluxoids leads to an additional Magnus type force due to proton circulation around the vortex. Pinning in the core of an NS may thus have a dramatic impact on the vortex dynamics, and therefore on the magnetorotational evolution of the star.

scholarly journals Global dynamics of international migration systems across South–South, North–North, and North–South flows, 1990–2015

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Diego F. Leal ◽  
Nicolas L. Harder
Keyword(s):  
International Migration ◽  
Network Effects ◽  
Global Dynamics ◽  
Core Set ◽  
Migration Dynamics ◽  
Key Drivers ◽  
Migration Flows ◽  
And Migration ◽  
Migration Systems

AbstractEvidence from 184 countries over the span of 25 years is gathered and analyzed to understand North–North, South–South, and North–South international migration flows. Conceptually, the analysis borrows from network theory and Migration Systems Theory (MST) to develop a model to characterize the structure and evolution of international migration flows. Methodologically, the Stochastic Actor-oriented Model of network dynamics is used to jointly model the three types of flows under analysis. Results show that endogenous network effects at the monadic, dyadic, and triadic levels of analysis are relevant to understand the emergence and evolution of migration flows. The findings also show that a core set of non-network covariates, suggested by MST as key drivers of migration flows, does not always explain migration dynamics in the systems under analysis in a consistent fashion; thus, suggesting the existence of important levels of heterogeneity inherent to these three types of flows. Finally, evidence related to the role of political instability and countries’ care deficits is also discussed as part of the analysis. Overall, the results highlight the importance of analyzing flows across the globe beyond typically studied migratory corridors (e.g., North–South flows) or regions (e.g., Europe).

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