scholarly journals Neutron stars: history of the magnetic field decay

2012 ◽  
Vol 8 (S291) ◽  
pp. 408-410
Author(s):  
Andrei P. Igoshev ◽  
Alexander F. Kholtygin
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Birth Rate ◽  
Initial Period ◽  
Universal Function ◽  
Initial Surface ◽  
Surface Magnetic Field ◽  
History Of ◽  
Field Decay ◽  
The Magnetic Field

AbstractUsing the data of the ATNF pulsar catalog we study the relation connected the real age t of young neutron stars (NS) and their spin-down age τ. We suppose that this relation is independent from both initial period of the NS and its initial surface magnetic field, and that the laws of the surface magnetic field decay are similar for all NSs in the Milky Way. We further assume that the birth-rate of pulsars was constant during at least last 200 million years. With these assumptions we were able to restore the history of the magnetic field decay for the galactic NSs. We reconstruct the universal function f(t) = B(t)/B0, where B0 is the initial magnetic field and B(t) is the magnetic field of NS at the age t. The function f(t) can be fitted by a power law with power index α = −1.17.

scholarly journals Mutual influence of magnetic field decay and thermal evolution of rotational neutron stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 586-588
Author(s):  
Xia Zhou ◽  
Miao Kang ◽  
Na Wang
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Mutual Influence ◽  
Thermal Evolution ◽  
Chemical Heating ◽  
Field Decay ◽  
The Magnetic Field

AbstractThe effect of magnetic field decay on the chemical heating and thermal evolution of neutron stars is discussed. Our main goal is to study how chemical heating mechanisms and thermal evolution are changed by field decay and how magnetic field decay is modified by the thermal evolution. We show that the effect of chemical heating is suppressed by the star spin-down through decaying magnetic field at a later stage; magnetic field decay is delayed significantly relative to stars cooling without heating mechanisms; compared to typical chemical heating, the decay of the magnetic field can even cause the temperature to turn down at a later stage.

scholarly journals Magnetic Field Decay, or Just Period-Dependent Beaming?

2004 ◽  
Vol 218 ◽  
pp. 41-44 ◽  
Author(s):  
Joeri van Leeuwen ◽  
Frank Verbunt
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Velocity Distribution ◽  
Neutron Stars ◽  
Time Scale ◽  
Radio Pulsar ◽  
New Born ◽  
Field Decay ◽  
The Magnetic Field

Several recent papers conclude that radio-pulsar magnetic fields decay on a time-scale of 10 Myr, apparently contradicting earlier results. We have implemented the methods of these papers in our code and show that this preference for rapid field decay is caused by the assumption that the beaming fraction does not depend on the period. When we do include this dependence, we find that the observed pulsar properties are reproduced best when the modeled field does not decay. When we assume that magnetic fields of new-born neutron stars are from a distribution sufficiently wide to explain magnetars, the magnetic field and period distributions we predict for radio are pulsars wider than observed. Finally we find that the observed velocities overestimate the intrinsic velocity distribution.

scholarly journals The Evolution of the Magnetic Fields of Neutron Stars

1992 ◽  
Vol 128 ◽  
pp. 26-34
Author(s):  
Dipankar Bhattacharya
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Theoretical Models ◽  
Radio Pulsars ◽  
Secular Evolution ◽  
History Of ◽  
Field Decay ◽  
The Magnetic Field

AbstractThe evolution of the magnetic field strength plays a major role in the life history of a neutron star. In this article the observational evidence of field evolution, in particular that of field decay and magnetic alignment, are critically examined. It is concluded that the observed decay of the spindown torque on radio pulsars cannot be caused by a secular evolution of the “obliqueness” of the neutron star, as suggested by some authors. Recent observations provide a strong indication that the decay of the magnetic field strength of a neutron star may be closely related to its evolution in a binary system. Theoretical models for such an evolution are discussed.

scholarly journals Formation of millisecond pulsars - NS initial mass and EOS constraints

2012 ◽  
Vol 8 (S290) ◽  
pp. 109-112
Author(s):  
Michał Bejger ◽  
Morgane Fortin ◽  
Paweł Haensel ◽  
J. Leszek Zdunik
Keyword(s):  
Magnetic Field ◽  
Equation Of State ◽  
Neutron Stars ◽  
Equations Of State ◽  
Recent Measurement ◽  
Millisecond Pulsar ◽  
Low Mass ◽  
Field Decay ◽  
The Magnetic Field ◽  
Account Interaction

AbstractRecent measurement of a high millisecond pulsar mass (PSR J1614-2230, 1.97± 0.04 M⊙) compared with the low mass of PSR J0751+1807 (1.26± 0.14 M⊙) indicates a large span of masses of recycled pulsars and suggests a broad range of neutron stars masses at birth. We aim at reconstructing the pre-accretion masses for these pulsars while taking into account interaction of the magnetic field with a thin accretion disk, magnetic field decay and relativistic 2D solutions for stellar configurations for a set of equations of state. We briefly discuss the evolutionary scenarios leading to the formation of these neutron stars and study the influence of the equation of state.

THE SPIN-UP OF ACCRETING NEUTRON STARS IN BINARY SYSTEMS

2011 ◽  
Vol 20 (10) ◽  
pp. 2019-2022
Author(s):  
J. WANG ◽  
C. M. ZHANG ◽  
Y. H. ZHAO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Binary Systems ◽  
Initial Conditions ◽  
Initial Period ◽  
Spin Period ◽  
The Magnetic Field ◽  
Initial Magnetic Field

In binary systems, the rotation of neutron stars can be spun up by the accreted material, and at the same time the decay of their magnetic fields occur in the accretion phase. As a result, the spin period may arrive at a minimum of about 1.5 ms, corresponding to a bottom value of the magnetic field ~ 108 G. Taking the conditions: (i) initial magnetic field varying from 1011 G to 1013 G while setting period as 100 s, (ii) initial period as 1–100 s at B = 5 × 1012 G , we find that this minimum of spin period seems independent of these initial conditions.

scholarly journals MAGNETIC FIELDS IN ACCRETION DISCS AROUND NEUTRON STARS — CONSEQUENCES FOR THE CHANGE OF SPIN

2013 ◽  
Vol 23 ◽  
pp. 106-110
Author(s):  
LUCA NASO ◽  
JOHN MILLER ◽  
WLODEK KLUŹNIAK
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Magnetic Field Profile ◽  
History Of ◽  
The One ◽  
The Universe ◽  
The Magnetic Field

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron stars spun up by an accretion disk, depends sensitively on the magnetic field structure, and yet highly idealized models from the 80s are still being used for calculating the magnetic field components. We present a possible way of improving the currently used models with a semi-analytic approach. The resulting magnetic field profile of both the poloidal and the toroidal component can be very different from the one suggested previously. This might dramatically change our picture of which parts of the disk tend to spin the star up or down.

scholarly journals Population synthesis of young neutron stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 411-413
Author(s):  
Andrei P. Igoshev ◽  
Alexander F. Kholtygin
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Supernova Explosion ◽  
Population Synthesis ◽  
Surface Magnetic Field ◽  
The Galaxy ◽  
The Mean ◽  
Field Decay

AbstractWe investigate the fortune of young neutron stars (NS) in the whole volume of the Milky Way with new code for population synthesis. We start our modeling from the birth of massive OB stars and follow their motion in the Galaxy up to the Supernova explosion. Next we integrate the equations of motion of NS in the averaged gravitational potential of the Galaxy. We estimate the mean kick velocities from a comparison the model Z and R-distributions of radio emitting NS with that for galactic NS accordingly ATNF pulsar catalog. We follow the history of the rotational velocity and the surface magnetic field of NS taking into account the significant magnetic field decay during the first million year of a neutron star's life. The derived value for the mean time of ohmic decay is 2.3ċ105 years. We model the subsample of galactic radio pulsars which can be detected with available radio telescopes, using a radio beaming model with inhomogeneous distribution of the radio emission in the cone. The distributions functions of the pulsar periods P, period derivatives Ṗ and surface magnetic fields B appear to be in a close agreement with those obtained from an ensemble of neutron stars in the ATNF catalogue.

Conditions for jet formation in accreting neutron stars: the magnetic field decay

2010 ◽  
Vol 6 (S275) ◽  
pp. 309-310
Author(s):  
Federico García ◽  
Deborah N. Aguilera ◽  
Gustavo E. Romero
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Compact Objects ◽  
Jet Formation ◽  
Field Diffusion ◽  
Induction Equation ◽  
Strong Surface ◽  
Field Decay ◽  
The Magnetic Field

AbstractAccreting neutron stars can produce jets only if they are weakly magnetized (B ~ 108 G). On the other hand, neutron stars are compact objects born with strong surface magnetic fields (B ~ 1012 G). In this work we study the conditions for jet formation in a binary system formed by a neutron star and a massive donor star once the magnetic field has decayed due to accretion. We solve the induction equation for the magnetic field diffusion in a realistic neutron star crust and discuss the possibility of jet launching in systems like the recently detected Supergiant Fast X-ray Transients.

scholarly journals Magnetic field evolution in magnetars

2012 ◽  
Vol 8 (S291) ◽  
pp. 425-427
Author(s):  
Yasufumi Kojima
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Neutron Stars ◽  
Dipole Field ◽  
Polar Field ◽  
Nonlinear Coupling ◽  
Strong Magnetic Fields ◽  
Field Decay ◽  
The Magnetic Field

AbstractDynamics of magnetic field decay is numerically studied. For neutron stars with strong magnetic fields, the Hall drift timescale in their crust is very short, and therefore the evolution is significantly affected. The nonlinear coupling between poloidal and toroidal components of the magnetic field is studied. It is also found that the polar field at the surface is highly distorted during the Hall drift timescale. For example, polar dipole field-strength temporarily decreases not by dissipation but by advection. This fact suggests that the dipole field-strength is not sufficient to determine the border between pulsars and magnetars.

scholarly journals Secondary Components of Binary Pulsars & Magnetic Field Decay in Neutron Stars

1987 ◽  
Vol 125 ◽  
pp. 407-407
Author(s):  
Shrinivas R. Kulkarni
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Neutron Stars ◽  
White Dwarf ◽  
Optical Counterpart ◽  
Surface Magnetic Field ◽  
Binary Pulsars ◽  
Field Decay

We report the discovery of white dwarf secondaries in 0655+64 and 0820+02 systems. In the 2303+46 system, we do not find any optical counterpart suggesting that the companion is another neutron star. The existence of a cool and therefore old white dwarf in the 0655+64 system implies that the surface magnetic field of neutron stars stops decaying beyond some value(s) of field strength.

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