共查询到20条相似文献，搜索用时 15 毫秒
1.
Armen Sedrakian James M. Cordes 《Monthly notices of the Royal Astronomical Society》1999,307(2):365-375
We show that the crust–core interface in neutron stars acts as a potential barrier to the peripheral neutron vortices approaching the interface in the model in which these are coupled to the proton vortex clusters. This elementary barrier arises because of the interaction of vortex magnetic flux with the Meissner currents set up by the crustal magnetic field at the interface. The dominant part of the force is derived from the cluster–interface interaction. As a result of the stopping of the continuous neutron vortex current through the interface, angular momentum is stored in the superfluid layers in the vicinity of the crust–core interface during the interglitch period. Discontinuous annihilation of proton vortices at the boundary restores the neutron vortex current and spins up the observable crust on short time-scales, leading to a glitch in the spin characteristics of a pulsar. 相似文献
2.
The theory of the relaxation of pulsar angular velocity is compared with observational data for the first eight glitches of the Vela pulsar. Solutions of the inverse problem in relaxation theory are obtained in the regions of exponential and linear relaxation in the core of the neutron star. From these solutions, a distribution of vortices is found that results in the observed relaxation of the pulsar's angular velocity. It is shown that the pinning of neutron vortices plays the primary role in the region of exponential relaxation, while in the region of linear relaxation one must allow for the variation of the angular velocity of the superfluid component. 相似文献
3.
D. M. Sedrakian 《Astrophysics》2000,43(3):275-281
The influence of the effect of entrainment of superconducting protons by superfluid neutrons on the distribution of neutron
vortices in a rotating neutron star is investigated. It is shown that the proton vortex clusters generated by entrainment
currents create the magnetic structure of a neutron vortex. The average magnetic field induction in a neutron vortex is calculated.
The presence of the magnetic field of a neutron vortex considerably alters the radius of the vortex zone. The width of the
vortex-free zone at the surface of the neutron star’s core increases, reaching macroscopic values on the order of several
meters. This result considerably changes earlier concepts of the distribution of neutron vortices in a neutron star.
Translated from Astrofizika, Vol. 43, No. 3, pp. 377-386, July–September, 2000. 相似文献
4.
P. B. Jones 《Monthly notices of the Royal Astronomical Society》2006,371(3):1327-1333
Neutron star inner cores with several charged baryonic components are likely to be analogues of the two-gap superconductor which is of current interest in condensed-matter physics. Consequently, type I superconductivity is less probable than type II but may nevertheless be present in some intervals of matter density. The intermediate-state structure formed at finite magnetic flux densities after the superconducting transitions is subject to buoyancy, frictional and neutron vortex interaction forces. These are estimated and it is shown that the most important frictional force is that produced by the stable stratification of neutron star matter, the irreversible process being diffusion in the normal, finite magnetic flux density, parts of the structure. The length-scale of the structure, in directions perpendicular to the local magnetic field is of crucial importance. For small scales, the flux comoves with the neutron vortices, as do the proton vortices of a type II superconductor. But for much larger length-scales, flux movement tends to that expected for normal charged Fermi systems. 相似文献
5.
Fluctuational mechanism for the formation of proton vortices in the superfluid core of neutron stars
The Gibbs thermodynamic potential of a proton vortex interacting with the normal core of a neutron vortex of radius r << λ (λ is the penetration depth) that is parallel to it and has an outer boundary of radius b is calculated. It is shown that, under
this assumption, the capture of only one vortex by the core is energetically favorable. The force acting on the proton vortex
owing to the entrained current is found and it is always directed toward the core. The corresponding force for a proton antivortex
is directed toward the outer boundary of the neutron vortex. The Ginzburg-Landau equation is solved for a vortex-antivortex
system and its Gibbs function is calculated. It is shown that at large distances from the core, vortex-antivortex pairs can
form because of fluctuations. Acted on by the entrainment current, the antivortex moves outward, while the vortex stays inside
the neutron vortex. It is shown that the best conditions for fluctuational pair production, followed by separation, exist
near the outer boundary. It is shown that new proton vortices can develop only in a region where the entrainment magnetic
field strength H (ρ) > HC1 (HC1 is the lower critical field).
__________
Translated from Astrofizika, Vol. 51, No. 1, pp. 139–149 (February 2008). 相似文献
6.
K. Glampedakis N. Andersson D. I. Jones 《Monthly notices of the Royal Astronomical Society》2009,394(4):1908-1924
We discuss short wavelength (inertial wave) instabilities present in the standard two-fluid neutron star model when there is sufficient relative flow along the superfluid neutron vortex array. We demonstrate that these instabilities may be triggered in precessing neutron stars, since the angular velocity vectors of the neutron and proton fluids are misaligned during precession. Our results suggest that the standard (Eulerian) slow precession that results for weak drag between the vortices and the charged fluid (protons and electrons) is not seriously affected by the instability. In contrast, the fast precession, which results when vortices are strongly coupled to the charged component, is generally unstable. The presence of this instability renders the standard (solid body) rotation model for free precession inconsistent and makes unsafe conclusions that have recently been drawn regarding neutron star interiors based on observations of precession in radio pulsars. 相似文献
7.
Jones 《Monthly notices of the Royal Astronomical Society》1998,296(1):217-224
It is usually assumed that pulsar glitches are caused by the large-scale unpinning of superfluid neutron vortices in the solid crust of a neutron star and that vortex motion relative to the crust is highly dissipative at low velocities, owing to the excitation of long-wavelength Kelvin waves. The force per unit length acting on a vortex as a result of Kelvin wave excitation has been calculated for a polycrystalline structure using the free-vortex Green function. An approximate upper limit for the maximum pinning force has been obtained which, for the form of structure anticipated, is many orders of magnitude too small for consistency with the observed size and frequency of glitches. The corollary is that glitches do not originate in the crust: the necessary pinning may be given by the interaction between neutron and proton vortices in the liquid core of the star. 相似文献
8.
Feynman's approach has been used to derive the equation of dynamics for type II superconductors from the Schr?dinger equation.
A closed set of equations for the study of vortex dynamics has been obtained. These equations have been used for calculating
electric and magnetic fields inside the core of neutron stars. In particular, the contribution of vortices to the generation
of electric and magnetic fields inside the core of the star is explicitly displayed. 相似文献
9.
The dynamics of the rotating two-component system in the core of a neutron star is considered. Equations of motion are derived with allowance for the pinning and depinning of neutron vortices, and general solutions of these equations are found for relatively small changes in the star's angular velocity. It is shown that these solutions can describe both a jump in a pulsar's angular velocity and its subsequent relaxation. The characteristic pinning and depinning times are estimated qualitatively from observational data for jumps in the angular velocity of the Vela pulsar.Translated from Astrofizika, Vol. 39, No. 4, pp. 593–604, October–December, 1996. 相似文献
10.
The superfluid core (“npe” phase) of a neutron star, consisting of superfluid neutrons, superconducting protons, and normal
electrons, is considered. The Gibbs thermodynamic potential of a superconducting proton vortex in a proton superconductor
of the second kind, interacting with the normal core of a neutron vortex of radius r ≪ λ parallel to it (λ is the depth of
penetration), is calculated. It is shown that under this assumption, the capture by the core of only one vortex turns out
to be energetically favored. The force exerted on the proton vortex by the entrainment current, always directed toward the
core, is found. The corresponding force for a proton antivortex is directed outward toward the outer boundary of the neutron
vortex. It is shown that the fluctuational formation of a vortex-antivortex pair is possible at a large distance from the
core under the action of the entrainment current. Under the action of the entrainment current, the antivortex travels outward,
while the vortex remains inside the neutron vortex. It is shown that the formation of new proton vortices is possible only
in the region in which the entrainment magnetic field strength is H(ρ) > Hcl (Hcl is the first critical field).
Translated from Astrofizika, Vol. 42, No. 2, pp. 225–234, April–June, 1999 相似文献
11.
A theory of the relaxation of pulsar angular velocity is compared with observational data for the first eight glitches of the Vela pulsar. The inverse problem of the theory of relaxation is considered and solutions of this problem in the regions of exponential and linear relaxation are found. General features in the distribution of neutron vortices in these regions immediately after a glitch are determined. It is shown that these properties may be related to the size of the glitch in pulsar angular velocity. 相似文献
12.
This paper is a discussion of some results from papers by followers of V. A. Ambartsumyan, whose fundamental articles serve
as the beginning of research on superdense stars: white dwarfs and neutron stars. Solutions of the Einstein equations are
given for the case of axial symmetry and are used to determine the integral parameters of rotating neutron stars and white
dwarfs. A theory of magnetic field generation in neutron stars has been developed and is consistent with the existence of
high, nonuniform magnetic fields on the order of 1014 G in pulsars. A theory has been proposed for the dynamics of neutron vortices and used to explain the observed relaxation
of the angular velocity of pulsars following glitches. 相似文献
13.
The Ginzburg-Landau equations are derived for the magnetic and gluomagnetic gauge fields of nonabelian semi-superfluid vortex
filaments in color superconducting cores of neutron stars containing a diquark CFL condensate. The interaction of the diquark
CFL condensate with the magnetic and gluomagnetic gauge fields is taken into account. The asymptotic values of the energies
of these filaments are determined from the quantization conditions. It is shown that a lattice of semi-superfluid vortex filaments
with a minimal quantum of circulation develops in the quark superconducting core during rotation of the star. The magnetic
field in the core of this vortex is on the order of 1018 G. A cluster of proton vortices, which develops in the hadron phase surrounding every superfluid neutron vortex owing to
an entrainment effect, creates new semi-superfluid vortex filaments with a minimal quantum of circulation in the quark superconducting
core.
Translated from Astrofizika, Vol. 51, No. 4, pp. 633–646 (November 2008). 相似文献
14.
The dynamics of the vortex lattice in the inner crust of a neutron star is considered. A general equation of motion is obtained
and solved under the assumption that there are regions of pinned and of free vortices. By comparing these solutions with observational
data for the Vela pulsar, the relative moments of inertia of regions of relaxation with the corresponding characteristic times
are calculated for two model stars with different equations of state. It is shown that the theory can be reconciled with observations
of the relaxation of pulsar angular velocity only for model stars with extremely stiff equations of state.
Translated from Astrofizika, Vol. 40, No. 1, pp. 67–76, January–March, 1997. 相似文献
15.
The superconducting proton condensate in the “npe” phase of a neutron star is considered. It is shown to be a type II superconductor
in the outer layer of the “npe” phase and a type I superconductor in the inner layer. Relaxation times are found for elastic
scattering of normal relativistic electrons from the magnetic fields of proton vortex clusters in the case of a type II superconductor
and elastic scattering from the magnetic field at the center of a neutron vortex in the case of a superconductor of the first
kind. The dynamical relaxation times obtained for the angular velocity of the pulsar PSR 0833—45 vary, as a function of the
density of the layers taking part in the relaxation process, within a fairly wide range: from several hours to l09 years. This means that the characteristic times of variation of pulsar angular velocity may be observed to lie in the indicated
time range.
Translated from Astrofizika, Vol. 40, No. 4, op. 497–506, October–December, 1997. 相似文献
16.
The vortex structure of the “npe” phase of neutron stars with a 3P2 superfluid neutron condensate of Cooper pairs is discussed. It is shown that, as the star rotates, superfluid neutron vortex
filaments described by a unitary ordering parameter develop in the “npe” phase. The entrainment of superconducting protons
by the rotating superfluid neutrons is examined. The entrainment effect leads to the appearance of clusters of proton vortices
around each neutron vortex and generates a magnetic field on the order of 1012 G. 3P2 neutron vortex filaments combine with quark semi-superfluid vortex filaments at the boundary of the “npe” and “CFL” phases.
At the boundary of the “Aen” and “npe” phases, they combine with 1S0 neutron vortex filaments. In this way, a unified vortex structure is formed. The existence of this structure and its collective
elastic oscillations explain the observed oscillations in the angular rotation velocity of pulsars. 相似文献
17.
N. Andersson T. Sidery G. L. Comer 《Monthly notices of the Royal Astronomical Society》2006,368(1):162-170
We discuss vortex-mediated mutual friction in the two-fluid model for superfluid neutron star cores. Our discussion is based on the general formalism developed by Carter and collaborators, which makes due distinction between transport velocity and momentum for each fluid. This is essential for an implementation of the so-called entrainment effect, whereby the flow of one fluid imparts momentum in the other and vice versa. The mutual friction follows by balancing the Magnus effect that acts on the quantized neutron vortices with resistivity due to the scattering of electrons off of the magnetic field with which each vortex core is endowed. We derive the form of the macroscopic mutual friction force which is relevant for a model based on smooth-averaging over a collection of vortices. We discuss the coefficients that enter the expression for this force, and the time-scale on which the two interpenetrating fluids in a neutron star core are coupled. This discussion confirms that our new formulation accords well with previous work in this area. 相似文献
18.
P. B. Jones 《Monthly notices of the Royal Astronomical Society》2009,397(2):1027-1031
The quantum phenomenon of spectral flow which has been observed in laboratory superfluids, such as 3 He-B, controls the drift velocity of proton type II superconductor vortices in the liquid core of a neutron star and so determines the rate at which magnetic flux can be expelled from the core to the crust. In the earliest and most active phases of the anomalous X-ray pulsars and soft-gamma repeaters, the rates are low and consistent with a large fraction of the active crustal flux not linking the core. If normal neutrons are present in an appreciable core matter-density interval, the spectral flow force limits flux expulsion in cases of rapid spin-down, such as in the Crab pulsar or in the propeller phase of binary systems. 相似文献
19.
We study thermal relaxation in a neutron star after internal heating events (outbursts) in the crust. We consider thin and thick spherically symmetric heaters, superfluid and non-superfluid crusts, stars with open and forbidden direct Urca processes in their cores. In particular, we analyze long-term thermal relaxation after deep crustal heating produced by nuclear transformations in fully or partly accreted crusts of transiently accreting neutron stars. This long-term relaxation has a typical relaxation time and an overall finite duration time for the crust to thermally equilibrate with the core. Neutron superfluidity in the inner crust greatly affects the relaxation if the heater is located in the inner crust. It shortens and unifies the time of emergence of thermal wave from the heater to the surface. This is important for the interpretation of observed outbursts of magnetars and transiently accreting neutron stars in quasi-persistent low-mass X-ray binaries. 相似文献
20.
G. A. Kovaltsov I. G. Usoskin L. G. Kocharov H. Kananen P. J. Tanskanen 《Solar physics》1995,158(2):395-398
Response of Alma-Ata neutron monitor for solar neutrons from the 15 June 1991 was studied. We considered this response as a test for various scenarios of proton acceleration during the flare. The analysis of neutron monitor is an evidence in favour of the assumption of two acts of proton acceleration at impulsive and post-impulsive phases of the flare. 相似文献