scholarly journals Magnetic field amplification in newly-born neutron stars

1996 ◽  
Vol 160 ◽  
pp. 435-436
Author(s):  
H.-J. Wiebicke ◽  
U. Geppert
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Gravitational Collapse ◽  
Dipole Field ◽  
Numerical Calculations ◽  
Selection Effects ◽  
Thermoelectric Effects ◽  
Field Amplification ◽  
Seed Field ◽  
Flux Conservation

AbstractWe present a scenario of magnetic field (MF) evolution of newly-born neutron stars (NSs). Numerical calculations show that in the hot phase of young NSs the MF can be amplified by thermoelectric effects, starting from a moderately strong seed-field. Therefore, there is no need to assume a 1012G dipole field immediately after the gravitational collapse of the supernova (SN) event. The widely accepted scenario for such a field to be produced by flux conservation during the collapse is critically discussed. Instead, it can be generated by amplification and selection effects in the first 104yrs, and by the subsequent fast ohmic decay of higher multipole components, when the NS cools down.

scholarly journals Magnetic field amplification in proto-neutron stars

2007 ◽  
Vol 479 (1) ◽  
pp. 167-176 ◽  
Author(s):  
L. Naso ◽  
L. Rezzolla ◽  
A. Bonanno ◽  
L. Paternò
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Field Amplification

scholarly journals Galactic and Metagalactic Magnetic Fields

1972 ◽  
Vol 44 ◽  
pp. 520-525
Author(s):  
K. Brecher
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Galactic Nuclei ◽  
Direct Result ◽  
Field Amplification ◽  
Recent Origin ◽  
Intergalactic Magnetic Field ◽  
Rotating Objects

All of the possible sources of primeval magnetic fields are examined and found to be inadequate to account for the observed galactic B-fields (if the magnetic fields in galaxies are the direct result of the condensation of a magnetized metagalactic medium). Field amplification in dense rotating objects (perhaps neutron stars or galactic nuclei) may be responsible for the bulk of such fields. Most of the (hypothetical) intergalactic B-field then originates in galaxies and is dragged along with the cosmic rays escaping from them. Limits are placed on the value of any present intergalactic magnetic field of either primordial or ‘recent’ origin.

scholarly journals SGRs and AXPs: Evidence for Delayed Amplification of Magnetic Field after Neutron Star Formation?

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Denis Leahy ◽  
Rachid Ouyed
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Birth Rate ◽  
Massive Stars ◽  
Robust Estimator ◽  
High Magnetic Fields ◽  
Field Amplification ◽  
Kolmogorov Smirnov

We present new analysis of the birth rate of AXPs and SGRS and their associated SNRs. Using Kolmogorov-Smirnov statistics together with parametric fits based on a robust estimator, we find a birth rate of ∼1/(1000 years) for AXPs/SGRs and their associated SNRs. These high rates suggest that all massive stars (greater than ∼(23–32)M⊙) give rise to remnants with magnetar-like fields. Observations indicate a limited fraction of high magnetic fields in these progenitors; thus our study is suggestive of magnetic field amplification. Dynamo mechanisms during the birth of the neutron stars require spin rates much faster than either observations or theory indicate. We propose that massive stars produce neutron stars with normal (∼1012 G) magnetic fields, which are then amplified to1014-1015 G after a delay of hundreds of years. The amplification is speculated to be a consequence of color ferromagnetism and to occur with a delay after the neutron star core reaches quark deconfinement density (i.e., the quark-nova scenario). The delayed amplification allows one to interpret simultaneously the high birth rate and high magnetic fields of AXPs/SGRs and their link to massive stars.

scholarly journals Recycled pulsars with multipolar magnetospheres from accretion-induced magnetic burial

2020 ◽  
Vol 499 (3) ◽  
pp. 3243-3254
Author(s):  
A G Suvorov ◽  
A Melatos
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Field Line ◽  
Dipole Field ◽  
Multipole Moments ◽  
Millisecond Pulsars ◽  
The Magnetic Field ◽  
Field Strengths

ABSTRACT Many millisecond pulsars are thought to be old neutron stars spun up (‘recycled’) during an earlier accretion phase. They typically have relatively weak (≲109 G) dipole field strengths, consistent with accretion-induced magnetic burial. Recent data from the Neutron Star Interior Composition Explorer indicate that hotspots atop the recycled pulsar PSR J0030–0451 are not antipodal, so that the magnetic field cannot be that of a centred dipole. In this paper it is shown that multipolarity is naturally expected in the burial scenario because of equatorial field line compression. Grad–Shafranov equilibria are constructed to show how magnetic multipole moments can be calculated in terms of various properties, such as the amount of accreted mass and the crustal equation of state.

scholarly journals THE IMPACT OF THERMODYNAMICS ON GRAVITATIONAL COLLAPSE: FILAMENT FORMATION AND MAGNETIC FIELD AMPLIFICATION

2012 ◽  
Vol 760 (2) ◽  
pp. L28 ◽  
Author(s):  
Thomas Peters ◽  
Dominik R. G. Schleicher ◽  
Ralf S. Klessen ◽  
Robi Banerjee ◽  
Christoph Federrath ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Gravitational Collapse ◽  
Filament Formation ◽  
Field Amplification ◽  
The Impact

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 Magnetic field amplification during gravitational collapse - influence of turbulence, rotation and gravitational compression

2012 ◽  
Vol 423 (4) ◽  
pp. 3148-3162 ◽  
Author(s):  
Sharanya Sur ◽  
Christoph Federrath ◽  
Dominik R. G. Schleicher ◽  
Robi Banerjee ◽  
Ralf S. Klessen
Keyword(s):  
Magnetic Field ◽  
Gravitational Collapse ◽  
Field Amplification ◽  
Gravitational Compression

scholarly journals Can one use Earth’s magnetic axial dipole field intensity to predict reversals?

2020 ◽  
Author(s):  
K Gwirtz ◽  
M Morzfeld ◽  
A Fournier ◽  
G Hulot
Keyword(s):  
Magnetic Field ◽  
Numerical Models ◽  
Dipole Field ◽  
Axial Dipole ◽  
Intensity Threshold ◽  
Magnetic Dipole Field ◽  
Model Hierarchy ◽  
Definition Of ◽  
Virtual Axial Dipole Moment ◽  
Prediction Strategy

Summary We study predictions of reversals of Earth’s axial magnetic dipole field that are based solely on the dipole’s intensity. The prediction strategy is, roughly, that once the dipole intensity drops below a threshold, then the field will continue to decrease and a reversal (or a major excursion) will occur. We first present a rigorous definition of an intensity threshold-based prediction strategy and then describe a mathematical and numerical framework to investigate its validity and robustness in view of the data being limited. We apply threshold-based predictions to a hierarchy of numerical models, ranging from simple scalar models to 3D geodynamos. We find that the skill of threshold-based predictions varies across the model hierarchy. The differences in skill can be explained by differences in how reversals occur: if the field decreases towards a reversal slowly (in a sense made precise in this paper), the skill is high, and if the field decreases quickly, the skill is low. Such a property could be used as an additional criterion to identify which models qualify as Earth-like. Applying threshold-based predictions to Virtual Axial Dipole Moment (VADM) paleomagnetic reconstructions (PADM2M and Sint-2000) covering the last two million years, reveals a moderate skill of threshold-based predictions for Earth’s dynamo. Besides all of their limitations, threshold-based predictions suggests that no reversal is to be expected within the next 10 kyr. Most importantly, however, we show that considering an intensity threshold for identifying upcoming reversals is intrinsically limited by the dynamic behavior of Earth’s magnetic field.

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