scholarly journals The Physics of Soft Gamma Repeaters

2000 ◽  
Vol 195 ◽  
pp. 245-254
Author(s):  
C. Thompson
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Strong Magnetic Fields ◽  
Dominant Source ◽  
Soft Gamma Repeaters ◽  
Physical Diagnostics ◽  
Fireball Model

I describe the evidence that Soft Gamma Repeaters are magnetars—neutron stars in which a decaying magnetic field (rather than rotation) is the dominant source of free energy. The focus here is on the bursting emission of these sources and on direct physical diagnostics of very strong magnetic fields (B ≳ 10 BQED = 4.4 × 1014 G). I also summarize the trapped fireball model of SGR outbursts, the influence of QED processes on their spectra and lightcurves, and the genetic connection between neutron star magnetism and the violent fluid motions in a collapsing supernova core.

scholarly journals Neutron stars velocities and magnetic fields

2018 ◽  
Vol 172 ◽  
pp. 07002
Author(s):  
Daryel Manreza Paret ◽  
A. Perez Martinez ◽  
Alejandro. Ayala ◽  
G. Piccinelli ◽  
A. Sanchez
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Strange Quark ◽  
Chemical Potential ◽  
Strange Quark Matter ◽  
Strong Magnetic Fields ◽  
Stars Velocities ◽  
Anisotropic Emission

We study a model that explain neutron stars velocities due to the anisotropic emission of neutrinos. Strong magnetic fields present in neutron stars are the source of the anisotropy in the system. To compute the velocity of the neutron star we model its core as composed by strange quark matter and analice the properties of a magnetized quark gas at finite temperature and density. Specifically we have obtained the electron polarization and the specific heat of magnetized fermions as a functions of the temperature, chemical potential and magnetic field which allow us to study the velocity of the neutron star as a function of these parameters.

scholarly journals Magnetars

2000 ◽  
Vol 177 ◽  
pp. 669-680
Author(s):  
Christopher Thompson
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Particle Emission ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Soft Gamma Repeaters

AbstractI summarize recent observational and theoretical advances in the understanding of the Soft Gamma Repeaters and the Anomalous X-ray Pulsars. Several direct physical arguments point to very strong magnetic fields (B> 10BQED= 4.4 × 1014 G) in SGR outbursts. The connection between these two classes of neutron stars is examined. Their persistent X-ray emission and spindown behavior are interpreted in the magnetar model, where a decaying magnetic field dominates all other sources of energy for radiative and particle emission. The response of a magnetic field to the violent motions in a supernova core is also examined, with a focus on mechanisms that may impart unusually large kicks.

scholarly journals Equations of State for Hadronic Matter and Mass-Radius Relations of Neutron Stars with Strong Magnetic Fields

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 48
Author(s):  
Chinatsu Watanabe ◽  
Naotaka Yoshinaga ◽  
Shuichiro Ebata
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Functional Form ◽  
Equations Of State ◽  
Hadronic Matter ◽  
Strong Magnetic Fields ◽  
Specific Choice ◽  
Important Object

Neutron star is an important object for us to verify the equation of state of hadronic matter. For a specific choice of equations of state, mass and radius of a neutron star are determined, for which there are constraints from observations. According to some previous studies, since the strong magnetic field acts as a repulsive force, there is a possibility that neutron stars with strong magnetic fields may have relatively heavier masses than other non-magnetized neutron stars. In this paper, the structure of a neutron star with a strong internal magnetic field is investigated by changing its internal functional form to see how much the neutron star can be massive and also how radius of a neutron star can be within a certain range.

ON THE INTERIOR OF THE NEUTRON STAR – I. NONLINEAR BEHAVIOR OF THE MAGNETIC FIELD

1994 ◽  
Vol 03 (03) ◽  
pp. 665-674
Author(s):  
RAMEN KUMAR PARUI
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Nonlinear Behavior ◽  
Wave Source ◽  
Strong Magnetic Fields ◽  
Outstanding Problem ◽  
The Magnetic Field

The generation of very strong magnetic fields on the surface of a neutron star has long been an outstanding problem. A spinning neutron star is considered as one of the anticipated gravitational wave sources. Here I have shown the nonlinear behavior of this magnetic field in the interior of both uncharged and charged neutron stars at equilibrium radii and obtained results favouring a gravitational wave source.

scholarly journals Onset of superconductivity and retention of magnetic fields in cooling neutron stars

2017 ◽  
Vol 13 (S337) ◽  
pp. 213-216
Author(s):  
Wynn C. G. Ho ◽  
Nils Andersson ◽  
Vanessa Graber
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Minimum Energy ◽  
Meissner Effect ◽  
Energy Conditions ◽  
Field Diffusion ◽  
Neutron Star Cooling ◽  
Proton Pairing

AbstractA superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest that magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core retains or is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 106 − 107yr. We estimate the size of flux free regions at 107yr to be ≲ 100m for a magnetic field of 1011G and possibly smaller for stronger field strengths.

scholarly journals Equatorial Geodesics Around the Magnetars

2017 ◽  
Vol 45 ◽  
pp. 1760050
Author(s):  
Viviane A. P. Alfradique ◽  
Orlenys N. Troconis ◽  
Rodrigo P. Negreiros
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Complete Solution ◽  
Compact Object ◽  
Relativistic Effects ◽  
Schwarzschild Solution ◽  
Soft Gamma Repeaters ◽  
Definition Of ◽  
The Magnetic Field

Neutron stars manifest themselves as different classes of astrophysical sources that are associated to distinct phenomenology. Here we focus our attention on magnetars (or strongly magnetized neutron stars) that are associated to Soft Gamma Repeaters and Anomalous X-ray Pulsars. The magnetic field on surface of these objects, reaches values greater than [Formula: see text] G. Under intense magnetic fields, relativistic effects begin to be decisive for the definition of the structure and evolution of these objects. We are tempted to question ourselves to how strengths fields affect the structure of neutron star. In this work, our objective is study and compare two solutions of Einstein-Maxwell equations: the Bonnor solution, which is an analytical solution that describe the exterior spacetime for a massive compact object which has a magnetic field that is characterize as a dipole field and a complete solution that describe the interior and exterior spacetime for the same source found by numerical methods). For this, we describe the geodesic equations generated by such solutions. Our results show that the orbits generated by the Bonnor solution are the same as described by numerical solution. Also, show that the inclusion of magnetic fields with values up to [Formula: see text]G in the center of the star does not modify sharply the particle orbits described around this star, so the use of Schwarzschild solution for the description of these orbits is a reasonable approximation.

scholarly journals Thermal luminosities of cooling neutron stars

2020 ◽  
Vol 496 (4) ◽  
pp. 5052-5071 ◽  
Author(s):  
A Y Potekhin ◽  
D A Zyuzin ◽  
D G Yakovlev ◽  
M V Beznogov ◽  
Yu A Shibanov
Keyword(s):  
Spectral Analysis ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Cooling Curves ◽  
Middle Aged ◽  
Superdense Matter ◽  
Strong Magnetic Fields ◽  
Stellar Core ◽  
Neutron Star Cooling

ABSTRACT Ages and thermal luminosities of neutron stars, inferred from observations, can be interpreted with the aid of the neutron star cooling theory to gain information on the properties of superdense matter in neutron-star interiors. We present a survey of estimated ages, surface temperatures, and thermal luminosities of middle-aged neutron stars with relatively weak or moderately strong magnetic fields, which can be useful for these purposes. The catalogue includes results selected from the literature, supplemented with new results of spectral analysis of a few cooling neutron stars. The data are compared with the theory. We show that overall agreement of theoretical cooling curves with observations improves substantially for models where neutron superfluidity in stellar core is weak.

scholarly journals EFFECT OF STRONG MAGNETIC FIELDS ON THE EQUILIBRIUM OF A DEGENERATE GAS OF NUCLEONS AND ELECTRONS

1996 ◽  
Vol 10 (23) ◽  
pp. 1141-1149 ◽  
Author(s):  
CHOON-LIN HO ◽  
V.R. KHALILOV ◽  
CHI YANG
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Strong Magnetic Field ◽  
Constant Magnetic Field ◽  
Fermi Momentum ◽  
Magnetic Field Induction ◽  
Strong Magnetic Fields ◽  
Field Induction ◽  
The Magnetic Field

We obtain the equations that define the equilibrium of a homogeneous relativistic gas of neutrons, protons and electrons in a constant magnetic field as applied to the conditions that probably occur near the center of neutron stars. We compute the relative densities of the particles at equilibrium and the Fermi momentum of electrons in the strong magnetic field as function of the density of neutrons and the magnetic field induction. Novel features are revealed as to the ratio of the number of protons to the number of neutrons at equilibrium in the presence of large magnetic fields.

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 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.

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