scholarly journals Searching optimum equations of state of neutron star matter in strong magnetic fields with rotation

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
C Watanabe ◽  
K Yanase ◽  
N Yoshinaga
Keyword(s):  
Neutron Star ◽  
Magnetic Fields ◽  
Equations Of State ◽  
Mean Field ◽  
Maximum Mass ◽  
Neutron Star Matter ◽  
Solar Mass ◽  
Strong Magnetic Fields ◽  
Relativistic Mean Field ◽  
Rho A

Abstract Masses and radii of neutron stars are obtained in the presence of strong magnetic fields together with rotation. Mass-radius relations are calculated using 11 equations of state (EoSs: GM1, TM1-a, TM1-b, TM2$\omega\rho$-a, TM2$\omega\rho$-b, NL3-a, NL3-b, NL3$\omega\rho$-a, NL3$\omega\rho$-b, DDME2-a and DDME2-b) in relativistic mean field (RMF) theory. Obtained masses are over and around twice the solar mass ($M_\odot$) for all EoSs in the presence of strong magnetic fields of $3 \times 10^{18}$ G at the center. For NL3$\omega\rho$-a and NL3$\omega\rho$-b EoSs, masses are more than $M=2.17\,M_\odot$(observed maximum mass: $2.14\,M_\odot$) even without magnetic fields. Rotational effects are found to be insignificant in any case, at least up to the Kepler frequency. Suitable EoSs are also selected concerning the constraint on the radius of a neutron star.

scholarly journals Constraints on Microscopic and Phenomenological Equations of State of Dense Matter from GW170817

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 204 ◽  
Author(s):  
Domenico Logoteta ◽  
Ignazio Bombaci
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Mean Field ◽  
Dense Matter ◽  
Neutron Star Matter ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Three Body ◽  
Good Agreement

We discuss the constraints on the equation of state (EOS) of neutron star matter obtained by the data analysis of the neutron star-neutron star merger in the event GW170807. To this scope, we consider two recent microscopic EOS models computed starting from two-body and three-body nuclear interactions derived using chiral perturbation theory. For comparison, we also use three representative phenomenological EOS models derived within the relativistic mean field approach. For each model, we determine the β -stable EOS and then the corresponding neutron star structure by solving the equations of hydrostatic equilibrium in general relativity. In addition, we calculate the tidal deformability parameters for the two neutron stars and discuss the results of our calculations in connection with the constraints obtained from the gravitational wave signal in GW170817. We find that the tidal deformabilities and radii for the binary’s component neutron stars in GW170817, calculated using a recent microscopic EOS model proposed by the present authors, are in very good agreement with those derived by gravitational waves data.

EQUATION OF STATE, MASS, RADIUS, MOMENT OF INERTIA, AND SURFACE GRAVITATIONAL REDSHIFT FOR NEUTRON STARS

1994 ◽  
Vol 03 (04) ◽  
pp. 813-838 ◽  
Author(s):  
G. BAO ◽  
E. ØSTGAARD ◽  
B. DYBVIK
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Total Mass ◽  
Equations Of State ◽  
Maximum Mass ◽  
Neutron Star Matter ◽  
Solar Mass ◽  
Moments Of Inertia ◽  
Gravitational Fields

We have calculated total masses and radii of neutron stars from the Tolman-Oppenheimer-Volkoff (TOV) equations (for matter in equilibrium in gravitational fields) and different equations of state for neutron-star matter. The calculations are done for different input central densities. We have also obtained pressure and density as functions of distance from the centre of the star, and moments of inertia and surface gravitational redshifts as functions of the total mass of the star. The maximum mass M max is for all equations of state in our calculations given by 1.65M⊙<M max <2.43M⊙ (where M⊙ is the solar mass), which agrees very well with “experimental” results. Corresponding radii R are given by 8.8 km <R<12.7 km , and a smaller central density will, in general, give a smaller mass and a larger radius.

THE EFFECT OF THE SCALAR-ISOVECTOR MESON FIELD ON HYPERON-RICH NEUTRON STAR MATTER

2008 ◽  
Vol 17 (07) ◽  
pp. 1293-1307 ◽  
Author(s):  
AI-JUN MI ◽  
WEI ZUO ◽  
ANG LI
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maximum Mass ◽  
Meson Field ◽  
Neutron Star Matter ◽  
Relativistic Mean Field ◽  
Strangeness Content ◽  
Positively Charged

We investigate the effect of the scalar-isovector δ-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the framework of the relativistic mean field theory. The influence of the δ-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npeμ neutron star matter. We find that inclusion of the δ-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the δ-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the δ-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, whereas inclusion of the δ-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the δ-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Σ hyperons.

scholarly journals Delta baryons in neutron-star matter under strong magnetic fields

2021 ◽  
Vol 57 (7) ◽  
Author(s):  
Veronica Dexheimer ◽  
Kauan D. Marquez ◽  
Débora P. Menezes
Keyword(s):  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Star Matter ◽  
Strong Magnetic Fields

scholarly journals COMPUTATION OF NEUTRON STAR STRUCTURE USING MODERN EQUATION OF STATE

2006 ◽  
Vol 21 (07) ◽  
pp. 1555-1565 ◽  
Author(s):  
G. H. BORDBAR ◽  
M. HAYATI
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Equations Of State ◽  
Maximum Mass ◽  
Neutron Star Matter ◽  
Radio Pulsars ◽  
Good Consistency ◽  
The Given ◽  
Neutron Star Radius ◽  
Star Structure

Using the modern equations of state derived from microscopic calculations, we have calculated the neutron star structure. For the neutron star, we have obtained a minimum mass about 0.1 M⊙ which is nearly independent of the equation of state, and a maximum mass between 1.47 M⊙ and 1.98 M⊙ which is strongly dependent on the equation of state. It is shown that among the equations of state of neutron star matter which we have used, the stiffest one leads to higher maximum mass and radius and lower central density. It is seen that the given maximum mass for the Reid-93 equation of state shows a good consistency with the accurate observations of radio pulsars. We have indicated that the thickness of neutron star crust is very small compared to the predicted neutron star radius.

scholarly journals Revisiting quark stars under the influence of strong magnetic fields

2012 ◽  
Vol 8 (S291) ◽  
pp. 458-458
Author(s):  
Debora Menezes
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Quark Matter ◽  
Mean Field ◽  
Heavy Ion ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Solar Mass ◽  
Strong Magnetic Fields ◽  
The Masses

AbstractQuark matter at finite temperature and subject to strong magnetic fields is possibly present in the early stages of heavy ion collisions and in the interior of protoneutron stars. We use the mean field approximation to investigate this type of quark matter described by the Nambu–Jona-Lasinio model. The energy per baryon of magnetized quark matter becomes more bound than nuclear matter made of iron nuclei, for magnetic fields around 1019 G. When the su(3) NJL model is applied to stellar matter, the maximum mass configurations are always above 1.45 solar masses and may be as high as 1.9 solar masses for a central magnetic field of 1018 G. These numbers are within the masses of observed neutron stars but exclude the recently measured star with 1.97 solar mass.The effect of the magnetic field on the effective quark masses and chemical potentials is only felt for quite strong magnetic fields, above 5 × 1018 G, with larger effects for the lower densities. Spin polarizations are more sensitive to weaker magnetic fields and are larger for lower temperatures and lower densities.

Magnetic field and EoS of neutron star matter at finite temperature

2015 ◽  
Vol 24 (07) ◽  
pp. 1550051
Author(s):  
Qingwu Wang ◽  
Xiaofu Lü
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Finite Temperature ◽  
Mean Field Theory ◽  
Mean Field ◽  
Mass Term ◽  
Baryon Density ◽  
Neutron Star Matter ◽  
Relativistic Mean Field ◽  
Inflection Points

In this paper, magnetic field and equation of state (EoS) of neutron star matter are studied under relativistic mean field theory. A nonzero mass term of magnetic field in the Lagrangian is introduced, which depends on baryon density of charged particles. The magnetic field has not been treated as external as usual and the calculations of magnetic field strength at finite temperature reveal the existence of inflection points in certain densities.

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