Building mountains

2019 ◽  
pp. 312-360
Author(s):  
Nils Andersson
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Observational Constraints ◽  
Neutron Star Crust

Different ways of generating continuous gravitational waves from a deformed rotating neutron star are discussed, starting with the physics of the neutron star crust and the modelling of elasticity and strain. A summary of observational constraints is provided. The role of the star’s interior magnetic field is considered. Accreting systems are explored and notion of precessing stars is discussed.

scholarly journals On the Nature of Magnetars

2004 ◽  
Vol 218 ◽  
pp. 265-266
Author(s):  
Ya. N. Istomin
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Gamma Ray ◽  
X Ray ◽  
Surface Magnetic Field ◽  
The Core ◽  
Neutron Star Crust ◽  
High Magnitude

The electromagnetic fields of magnetodipole radiation can penetrate to the conducting matter of a neutron star crust and create there electric currents and tangential magnetic fields of high magnitude. The solution obtained here has the form of surface magnetic field discontinuities propagating through the crust to the core. This model explains the phenomena of magnetars — Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars.

scholarly journals Conductivity of neutron star crust under superhigh magnetic fields and Ohmic decay of toroidal magnetic field of magnetar

2019 ◽  
Vol 68 (18) ◽  
pp. 180401
Author(s):  
Jian-Ling Chen ◽  
Hui Wang ◽  
Huan-Yu Jia ◽  
Zi-Wei Ma ◽  
Yong-Hong Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Toroidal Magnetic Field ◽  
Neutron Star Crust

scholarly journals Breaking stress of Coulomb crystals in the neutron star crust

2021 ◽  
Vol 2103 (1) ◽  
pp. 012002
Author(s):  
A A Kozhberov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Zero Point ◽  
Breaking Stress ◽  
Electrostatic Energy ◽  
Zero Temperature ◽  
Coulomb Crystal ◽  
Neutron Star Crust ◽  
Crystal Model ◽  
Coulomb Crystals

Abstract It is generally accepted that the Coulomb crystal model can be used to describe matter in the neutron star crust. In [1] we study the properties of deformed Coulomb crystals and how their stability depends on the polarization of the electron background. The breaking stress in the crust σmax at zero temperature was calculated based on the analysis of the electrostatic energy and the phonon spectrum of the Coulomb crystal. In this paper, I briefly discuss the influence of zero-point, thermal contributions and the internal magnetic field on σmax.

scholarly journals ENTRAINMENT COEFFICIENT AND EFFECTIVE MASS FOR CONDUCTION NEUTRONS IN NEUTRON STAR CRUST: MACROSCOPIC TREATMENT

2006 ◽  
Vol 15 (05) ◽  
pp. 777-803 ◽  
Author(s):  
BRANDON CARTER ◽  
NICOLAS CHAMEL ◽  
PAWEL HAENSEL
Keyword(s):  
Neutron Star ◽  
Effective Mass ◽  
Quantum Mechanical ◽  
Independent Mobility ◽  
Ionic Charge ◽  
Neutron Star Crust ◽  
Two Fluid ◽  
Mobility Coefficient ◽  
A Current

Phenomena such as pulsar frequency glitches are believed to be attributable to differential rotation of a current of "free" superfluid neutrons at densities above the "drip" threshold in the ionic crust of a neutron star. Such relative flow is shown to be locally describable by adaption of a canonical two-fluid treatment that emphasizes the role of the momentum covectors constructed by differentiation of action with respect to the currents, with allowance for stratification whereby the ionic number current may be conserved even when the ionic charge number Z is altered by beta processes. It is demonstrated that the gauge freedom to make different choices of the chemical basis determining which neutrons are counted as "free" does not affect their "superfluid" momentum covector, which must locally have the form of a gradient (though it does affect the "normal" momentum covector characterizing the protons and those neutrons that are considered to be "confined" in the nuclei). It is shown how the effect of "entrainment" (whereby the momentum directions deviate from those of the currents) is controlled by the (gauge-independent) mobility coefficient [Formula: see text], estimated in recent microscopical quantum mechanical investigations, which suggest that the corresponding (gauge-dependent) "effective mass" m⋆ of the free neutrons can become very large in some layers. The relation between this treatment of the crust layers and related work (using different definitions of "effective mass") intended for the deeper core layers is discussed.

scholarly journals Magnetic-field evolution with large-scale velocity circulation in a neutron-star crust

2020 ◽  
Vol 494 (3) ◽  
pp. 3790-3798 ◽  
Author(s):  
Yasufumi Kojima ◽  
Kazuki Suzuki
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Lorentz Force ◽  
Large Scale ◽  
Magnetic Energy ◽  
Fluid Motion ◽  
Navier Stokes Equation ◽  
Ohmic Dissipation ◽  
Neutron Star Crust ◽  
Field Evolution

ABSTRACT We examine the effects of plastic flow that appear in a neutron-star crust when a magnetic stress exceeds the threshold. The dynamics involved are described using the Navier–Stokes equation comprising the viscous-flow term, and the velocity fields for the global circulation are determined using quasi-stationary approximation. We simulate the magnetic-field evolution by taking into consideration the Hall drift, Ohmic dissipation, and fluid motion induced by the Lorentz force. The decrease in the magnetic energy is enhanced, as the energy converts to the bulk motion energy and heat. It is found that the bulk velocity induced by the Lorentz force has a significant influence in the low-viscosity and strong-magnetic-field regimes. This effect is crucial near magnetar surfaces.

scholarly journals The role of magnetic field geometry in the evolution of neutron star merger accretion discs

2019 ◽  
Vol 490 (4) ◽  
pp. 4811-4825 ◽  
Author(s):  
I M Christie ◽  
A Lalakos ◽  
A Tchekhovskoy ◽  
R Fernández ◽  
F Foucart ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Large Scale ◽  
Gamma Ray ◽  
Long Duration ◽  
Field Geometry ◽  
General Relativistic ◽  
R Process ◽  
Magnetohydrodynamic Simulations

ABSTRACT Neutron star mergers are unique laboratories of accretion, ejection, and r-process nucleosynthesis. We used 3D general relativistic magnetohydrodynamic simulations to study the role of the post-merger magnetic geometry in the evolution of merger remnant discs around stationary Kerr black holes. Our simulations fully capture mass accretion, ejection, and jet production, owing to their exceptionally long duration exceeding 4 s. Poloidal post-merger magnetic field configurations produce jets with energies Ejet ∼ (4–30) × 1050 erg, isotropic equivalent energies Eiso ∼ (4–20) × 1052 erg, opening angles θjet ∼ 6–13°, and durations tj ≲ 1 s. Accompanying the production of jets is the ejection of $f_\mathrm{ej}\sim 30\!-\!40{{\ \rm per\ cent}}$ of the post-merger disc mass, continuing out to times >1 s. We discover that a more natural, purely toroidal post-merger magnetic field geometry generates large-scale poloidal magnetic flux of alternating polarity and striped jets. The first stripe, of $E_\mathrm{jet}\simeq 2\times 10^{48}\, \mathrm{erg}$, Eiso ∼ 1051 erg, θjet ∼ 3.5–5°, and tj ∼ 0.1 s, is followed by ≳4 s of striped jet activity with $f_\mathrm{ej}\simeq 27{{\ \rm per\ cent}}$. The dissipation of such stripes could power the short-duration gamma-ray burst (sGRB) prompt emission. Our simulated jet energies and durations span the range of sGRBs. We find that although the blue kilonova component is initially hidden from view by the red component, it expands faster, outruns the red component, and becomes visible to off-axis observers. In comparison to GW 170817/GRB 170817A, our simulations underpredict the mass of the blue relative to red component by a factor of few. Including the dynamical ejecta and neutrino absorption may reduce this tension.

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