Relativistic equations of state in a Thomas-Fermi approach for neutron stars

2002 ◽  
Vol 65 (4) ◽  
Author(s):  
A. L. Espíndola ◽  
D. P. Menezes
Keyword(s):  
Neutron Stars ◽  
Equations Of State ◽  
Thomas Fermi ◽  
Relativistic Equations

Supernova and neutron stars with relativistic equations of state

1992 ◽  
Vol 276 (4) ◽  
pp. 393-397 ◽  
Author(s):  
K. Sumiyoshi ◽  
H. Toki ◽  
R. Brockmann
Keyword(s):  
Neutron Stars ◽  
Equations Of State ◽  
Relativistic Equations

scholarly journals Neutron Star Properties with Relativistic Equations of State

1998 ◽  
Vol 07 (03) ◽  
pp. 301-339 ◽  
Author(s):  
H. Huber ◽  
F. Weber ◽  
M. K. Weigel ◽  
Ch. Schaab
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Neutron Star Matter ◽  
Hartree Fock ◽  
Standard Neutron ◽  
Relativistic Equations

We study the properties of neutron stars adopting relativistic equations of state of neutron star matter, calculated in the framework of the relativistic Brueckner–Hartree–Fock approximation for electrically charge neutral neutron star matter in beta–equilibrium. For higher densities more baryons (hyperons etc.) are included by means of the relativistic Hartree– or Hartree–Fock approximation. The special features of the different approximations and compositions are discussed in detail. Besides standard neutron star properties special emphasis is put on the limiting periods of neutron stars, for which the Kepler criterion and gravitation–reaction instabilities are considered. Furthermore the cooling behaviour of neutron stars is investigated, too. For comparison we also give the outcome for some nonrelativistic equations of state.

scholarly journals Updated universal relations for tidal deformabilities of neutron stars from phenomenological equations of state

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Daniel A. Godzieba ◽  
Rossella Gamba ◽  
David Radice ◽  
Sebastiano Bernuzzi
Keyword(s):  
Neutron Stars ◽  
Equations Of State ◽  
Phenomenological Equations

scholarly journals Beyond second-order convergence in simulations of magnetized binary neutron stars with realistic microphysics

2019 ◽  
Vol 490 (3) ◽  
pp. 3588-3600 ◽  
Author(s):  
E R Most ◽  
L Jens Papenfort ◽  
L Rezzolla
Keyword(s):  
Neutron Stars ◽  
Fourth Order ◽  
Finite Temperature ◽  
Equations Of State ◽  
Magnetic Energy ◽  
Second Order ◽  
Conservative Finite Difference Scheme ◽  
Order Scheme ◽  
Convergence Orders ◽  
The Impact

ABSTRACT We investigate the impact of using high-order numerical methods to study the merger of magnetized neutron stars with finite-temperature microphysics and neutrino cooling in full general relativity. By implementing a fourth-order accurate conservative finite-difference scheme we model the inspiral together with the early post-merger and highlight the differences to traditional second-order approaches at the various stages of the simulation. We find that even for finite-temperature equations of state, convergence orders higher than second order can be achieved in the inspiral and post-merger for the gravitational-wave phase. We further demonstrate that the second-order scheme overestimates the amount of proton-rich shock-heated ejecta, which can have an impact on the modelling of the dynamical part of the kilonova emission. Finally, we show that already at low resolution the growth rate of the magnetic energy is consistently resolved by using a fourth-order scheme.

scholarly journals Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

Universe ◽  
2020 ◽  
Vol 6 (5) ◽  
pp. 63
Author(s):  
Hui Wang ◽  
Zhi-Fu Gao ◽  
Huan-Yu Jia ◽  
Na Wang ◽  
Xiang-Dong Li
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
General Expression ◽  
Equations Of State ◽  
Rotation Period ◽  
Ohmic Dissipation ◽  
Hartree Fock ◽  
Induction Equation ◽  
The Magnetic Field

Young pulsars are thought to be highly magnetized neutron stars (NSs). The crustal magnetic field of a NS usually decays at different timescales in the forms of Hall drift and Ohmic dissipation. The magnetization parameter ω B τ is defined as the ratio of the Ohmic timescale τ O h m to the Hall drift timescale τ H a l l . During the first several million years, the inner temperature of the newly born neutron star cools from T = 10 9 K to T = 1.0 × 10 8 K, and the crustal conductivity increases by three orders of magnitude. In this work, we adopt a unified equations of state for cold non-accreting neutron stars with the Hartree–Fock–Bogoliubov method, developed by Pearson et al. (2018), and choose two fiducial dipole magnetic fields of B = 1.0 × 10 13 G and B = 1.0 × 10 14 G, four different temperatures, T, and two different impurity concentration parameters, Q, and then calculate the conductivity of the inner crust of NSs and give a general expression of magnetization parameter for young pulsars: ω B τ ≃ ( 1 − 50 ) B 0 / ( 10 13 G) by using numerical simulations. It was found when B ≤ 10 15 G, due to the quantum effects, the conductivity increases slightly with the increase in the magnetic field, the enhanced magnetic field has a small effect on the matter in the low-density regions of the crust, and almost has no influence the matter in the high-density regions. Then, we apply the general expression of the magnetization parameter to the high braking-index pulsar PSR J1640-4631. By combining the observed arrival time parameters of PSR J1640-4631 with the magnetic induction equation, we estimated the initial rotation period P 0 , the initial dipole magnetic field B 0 , the Ohm dissipation timescale τ O h m and Hall drift timescale τ H a l l . We model the magnetic field evolution and the braking-index evolution of the pulsar and compare the results with its observations. It is expected that the results of this paper can be applied to more young pulsars.

scholarly journals Model Atmospheres for Cooling Neutron Stars

1987 ◽  
Vol 125 ◽  
pp. 459-459
Author(s):  
Roger W. Romani ◽  
Roger D. Blandford ◽  
Lars Hernquist
Keyword(s):  
Neutron Stars ◽  
Supernova Remnants ◽  
Equations Of State ◽  
Black Body ◽  
X Ray ◽  
Electron Heat ◽  
Parallel Field ◽  
Effective Temperatures ◽  
Calculated Model ◽  
Magnetic Case

The failure of Einstein X-ray observations to detect central neutron stars in most young supernova remnants (Helfand and Becker 1984) has provided interesting constraints on cooling theories (cf. review by Tsuruta 1985). The comparison of the measured fluxes with the predicted effective temperatures is sensitive to the nature of the emitted spectrum, commonly assumed to be blackbody. The presence of a substantial absorbing atmosphere can, however, produce significant departures. We have calculated model atmospheres for unmagnetized neutron stars with effective temperatures 105K ≦ Teff ≦ 106.5K using Los Alamos opacities and equations of state (Romani 1986). We consider a range of surface compositions, since the accretion of ∼10−19M⊙ will cover the surface to the X-ray photosphere and subsequent settling in the strong gravitational field can severely deplete the heavy species. In a low Z atmosphere (eg. He) the measured X-ray flux will substantially exceed the blackbody value–the Einstein limits on Teff are correspondingly lowered (eg. by ∼1.6 for SN1006 with a helium surface). For high Z atmospheres, the flux is close to the black body value, but prominent absorption edges are present. Recent calculations of the electron heat transport in magnetized neutron star envelopes (Hernquist 1984, 1985) have shown that, contrary to earlier estimates, magnetic fields will have a small effect on the heat flux (≳ 3 for parallel field geometries and ∼1 for tangled fields). Extension of the atmosphere computations to the magnetic case is important for comparison with X-ray observations of known pulsars.

FINITE TEMPERATURE EQUATIONS OF STATE FOR MIXED STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1249-1253
Author(s):  
DÉBORA P. MENEZES ◽  
C. PROVIDÊNCIA
Keyword(s):  
Field Theory ◽  
Neutron Stars ◽  
Quark Matter ◽  
Finite Temperature ◽  
Equations Of State ◽  
Mean Field Theory ◽  
Mean Field ◽  
Relativistic Mean Field Theory ◽  
Relativistic Mean Field

We investigate the properties of mixed stars formed by hadronic and quark matter in β-equilibrium described by appropriate equations of state (EOS) in the framework of relativistic mean-field theory. The calculations were performed for T=0 and for finite temperatures and also for fixed entropies with and without neutrino trapping in order to describe neutron and proto-neutron stars. The star properties are discussed. Maximum allowed masses for proto-neutron stars are much larger when neutrino trapping is imposed.

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