A FINITE TEMPERATURE RELATIVISTIC NUCLEAR MODEL FOR NEUTRON STARS IN A SLOW ROTATIONAL SCENARIO

2007 ◽  
Vol 16 (02n03) ◽  
pp. 341-345 ◽  
Author(s):  
ALEXANDRE MESQUITA ◽  
MOISES RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
BARDO E. J. BODMANN
Keyword(s):  
Neutron Stars ◽  
Finite Temperature ◽  
Mean Field ◽  
Dense Matter ◽  
Coupling Constants ◽  
Nuclear Model ◽  
Density Profiles ◽  
Stellar Objects ◽  
Relativistic Mean Field ◽  
Inertial Moment

We study the effects of temperature in hadron dense matter within a generalized relativistic mean field approach based on the naturalness of the coupling constants of the theory. The Lagrangian density of our formulation contains nonlinear self-couplings of the σ meson field coupled to baryons and to the ω and ϱ meson fields. Moreover, we use the Sommerfeld and Hartle approximations to extend our approach to the finite temperature domain and slow rotational scenario. Both Sommerfeld and Hartle approximation allows a drastic simplification of computational work while improving the capability of theoretical analysis of the role of temperature and rotation on properties of protoneutron stars. Our predictions indicate that in the slow rotating regimen, neutron stars density profiles as well as the maximum mass and the inertial moment of these stellar objects are well approximated by the zero temperature approximation.

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.

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.

scholarly journals Effects of symmetry energy on the radius and tidal deformability of neutron stars in the relativistic mean-field model

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Jinniu Hu ◽  
Shishao Bao ◽  
Ying Zhang ◽  
Ken’ichiro Nakazato ◽  
Kohsuke Sumiyoshi ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Symmetry Energy ◽  
Binary Star ◽  
Mean Field ◽  
Mass Region ◽  
Saturation Density ◽  
Coupling Constants ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Family

Abstract The radii and tidal deformabilities of neutron stars are investigated in the framework of the relativistic mean-field (RMF) model with different density-dependent behaviors of symmetry energy. To study the effects of symmetry energy on the properties of neutron stars, $\omega$ meson and $\rho$ meson coupling terms are included in a popular RMF Lagrangian, i.e., the TM1 parameter set, which is adopted for the widely used supernova equation of state (EoS) table. The coupling constants relevant to the vector–isovector meson, $\rho$, are refitted by a fixed symmetry energy at subsaturation density and its slope at saturation density, while other coupling constants remain the same as the original ones in TM1 so as to update the supernova EoS table. The radius and mass of maximum neutron stars are not so sensitive to the symmetry energy in these family TM1 parameterizations. However, the radii in the intermediate-mass region are strongly correlated with the slope of symmetry energy. Furthermore, the dimensionless tidal deformabilities of neutron stars are also calculated within the associated Love number, which is related to the quadrupole deformation of the star in a static external tidal field and can be extracted from the observation of a gravitational wave generated by a binary star merger. We find that its value at $1.4 \mathrm{M}_\odot$ has a linear correlation to the slope of symmetry energy, unlike that previously studied. With the latest constraints of tidal deformabilities from the GW170817 event, the slope of symmetry energy at nuclear saturation density should be smaller than $60$ MeV in the family TM1 parameterizations. This fact supports the usage of a lower symmetry energy slope for the updated supernova EoS, which is applicable to simulations of neutron star mergers. Furthermore, an analogous analysis is also done within the family IUFSU parameter sets. It is found that the correlations between the symmetry energy slope with the radius and tidal deformability at $1.4 \mathrm{M}_\odot$ have very similar linear relations in these RMF models.

A RELATIVISTIC MEAN FIELD THEORY FOR NUCLEAR MATTER AT T≠0

2004 ◽  
Vol 13 (07) ◽  
pp. 1177-1181
Author(s):  
ALEXANDRE MESQUITA ◽  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
MANFRED DILLIG ◽  
BARDO E. J. BODMANN
Keyword(s):  
Nuclear Matter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dense Matter ◽  
Baryon Number ◽  
Coupling Constants ◽  
Model Parameters ◽  
Static Properties ◽  
Relativistic Mean Field ◽  
Protoneutron Stars

We study effects of temperature in hadron dense matter within a generalized relativistic mean field approach based on the naturalness of the various coupling constants of the theory, The Lagrangian density of our formulation contains the fundamental baryon octet, nonlinear self-couplings of the σ and δ meson fields coupled to the baryons and to the ω and ρ meson fields. By adjusting the model parameters, after inclusion in a consistent way of chemical equilibrium, baryon number and electric charge conservation, our model describes static bulk properties of ordinary nuclear matter and neutron stars. In the framework of the Sommerfeld approximation, we extend our approach to the T≠0 domain. The Sommerfeld approximation allows a drastic simplification of computational work while improving the capability of the theoretical analysis of the role of temperature on static properties of protoneutron stars. We perform the calculations by using our nonlinear model, which we extend by considering trapped neutrinos introduced into the formalism by fixing the lepton fraction. Integrating the Tolman–Oppenheimer–Volkoff equations we have obtained standard plots for the mass and radius of protoneutron stars as a function of the central density and temperature. Our predictions include the determination of an absolute value for the protoneutron star limiting mass at low and intermediate temperature regimes.

scholarly journals Critical mass, moment of inertia and universal relations of rapidly rotating neutron stars with exotic matter

2017 ◽  
Vol 26 (11) ◽  
pp. 1750127 ◽  
Author(s):  
Smruti Smita Lenka ◽  
Prasanta Char ◽  
Sarmistha Banik
Keyword(s):  
Neutron Stars ◽  
Critical Mass ◽  
Rest Mass ◽  
Mean Field ◽  
Dense Matter ◽  
Moment Of Inertia ◽  
Rotating Stars ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
Mass Moment

We calculate moment of inertia of neutron star with different exotic constituents such as hyperons and antikaon condensates and study its variation with mass and spin frequency. The sets of equation-of-state (EoS), generated within the framework of relativistic mean field model with density-dependent couplings are adopted for the purpose. We follow the quasi-stationary evolution of rotating stars along the constant rest mass sequences, that varies considerably with different constituents in the EoS. We also explore the universal relations associated with some of the normalized properties, such as critical mass and moment of inertia for specific EoS or as a matter of fact constituents of the dense matter. Deviations in the universal relations for moment of inertia are observed at higher compactness. This study presents important results concerning the properties of neutron stars, that could be observationally verified in the near future using Square Kilometer Array telescope.

scholarly journals Highly Magnetized Neutron Stars in a Many-body Forces Formalism

2017 ◽  
Vol 45 ◽  
pp. 1760033
Author(s):  
Rosana O. Gomes ◽  
Cesar A. Z. Vasconcellos ◽  
Bruno Franzon ◽  
Stefan Schramm ◽  
Veronica Dexheimer
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Mean Field ◽  
Nuclear Interaction ◽  
Coupling Constants ◽  
Many Body ◽  
Poloidal Magnetic Field ◽  
Relativistic Mean Field ◽  
Body Forces ◽  
Consistent Solution

In this work, we study the effects of different magnetic field configurations in neutron stars described by a many-body forces formalism (MBF model). The MBF model is a relativistic mean field formalism that takes into account many-body forces by means of a meson field dependence of the nuclear interaction coupling constants. We choose the best parametrization of the model that reproduces nuclear matter properties at saturation and also describes massive neutron stars. We assume matter to be in beta-equilibrium, charge neutral and at zero temperature. Magnetic fields are taken into account both in the equation of state and in the structure of the stars by the self-consistent solution of the Einstein-Maxwell equations. We assume a poloidal magnetic field distribution and calculate its effects on neutron stars, showing its influence on the gravitational mass and deformation of the stars.

scholarly journals Hyperons and quarks in proto-neutron stars

2019 ◽  
Vol 486 (4) ◽  
pp. 5441-5447 ◽  
Author(s):  
J Roark ◽  
X Du ◽  
C Constantinou ◽  
V Dexheimer ◽  
A W Steiner ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Finite Temperature ◽  
Degrees Of Freedom ◽  
Mean Field ◽  
Large Mass ◽  
Stellar Structure ◽  
Stellar Rotation ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Impact

ABSTRACT In this work, we study matter in the cores of proto-neutron stars, focusing on the impact of their composition on the stellar structure. We begin by examining the effects of finite temperature (through a fixed entropy per baryon) and lepton fraction on purely nucleonic matter by making use of the DSH (Du, Steiner & Holt) model. We then turn our attention to a relativistic mean-field model containing exotic degrees of freedom, the Chiral Mean Field (CMF) model, again, under the conditions of finite temperature and trapped neutrinos. In the latter, since both hyperons and quarks are found in the cores of large-mass stars, their interplay and the possibility of mixtures of phases is taken into account and analysed. Finally, we discuss how stellar rotation can affect our results.

scholarly journals Relativistic density functional for nuclear matter

2019 ◽  
Vol 204 ◽  
pp. 05001
Author(s):  
Stefan Gmuca ◽  
Kristian Petrík ◽  
Jozef Leja
Keyword(s):  
Energy Density ◽  
Nuclear Matter ◽  
Density Functional ◽  
Mean Field ◽  
Dense Matter ◽  
Coupling Constants ◽  
Effective Coupling ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Rmf Model

In the present work, we have mapped the exchange Fock contributions from the Dirac–Hartree–Fock (DHF) approach for nuclear matter onto the direct Hartree terms. This results in the relativistic mean field (RMF) model with the density dependent couplings. The density dependence of the effective coupling constants thus reflects the exchange correlations. The exchange part of an energy density of the linear DHF model in dense matter is evaluated in a parameter-free closed form and, after the rearrangement of the terms, expressed as density functional.

THE INNER CRUST OF NEUTRON STARS IN RELATIVISTIC MEAN FIELD APPROACH

2008 ◽  
Vol 17 (09) ◽  
pp. 1765-1773 ◽  
Author(s):  
JIGUANG CAO ◽  
ZHONGYU MA ◽  
NGUYEN VAN GIAI
Keyword(s):  
Boundary Conditions ◽  
Neutron Stars ◽  
Mean Field ◽  
Bcs Theory ◽  
Neutron Density ◽  
Field Approach ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Density Distributions ◽  
Rmf Model

The microscopic properties and superfluidity of the inner crust in neutron stars are investigated in the framework of the relativistic mean field(RMF) model and BCS theory. The Wigner-Seitz(W-S) cell of inner crust is composed of neutron-rich nuclei immersed in a sea of dilute, homogeneous neutron gas. The pairing properties of nucleons in the W-S cells are treated in BCS theory with Gogny interaction. In this work, we emphasize on the choice of the boundary conditions in the RMF approach and superfluidity of the inner crust. Three kinds of boundary conditions are suggested. The properties of the W-S cells with the three kinds of boundary conditions are investigated. The neutron density distributions in the RMF and Hartree-Fock-Bogoliubov(HFB) models are compared.

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