scholarly journals Quantum Crystals in Neutron Stars

1974 ◽  
Vol 53 ◽  
pp. 133-150 ◽  
Author(s):  
V. Canuto ◽  
S. M. Chitre
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Solid Core ◽  
Many Body ◽  
The Core ◽  
Deep Interior ◽  
Body Techniques ◽  
Quantum Crystals ◽  
The Many ◽  
Orderly Arrangement

Using the many-body techniques appropriate for quantum crystals it is shown that the deep interior of a neutron star is most likely an orderly arrangement of neutrons, protons and hyperons forming a solid. It is shown that a liquid or gas arrangement would produce higher energy. If so, a neutron star can be viewed as two solids (crust and core) permeated by a layer of ordinary or (perhaps) superfluid liquid. Astronomical evidence is in favor of such a structure: the sudden jumps in the periods of the Crab and Vela pulsars that differ by a factor of ∼ 102 can be easily explained by the star-quake model. If the Crab is less massive than Vela (i.e., if it is not dense enough to have a solid core), the star-quakes take place in the crust whereas for Vela they occur in the core.

scholarly journals Impact of chiral hyperonic three-body forces on neutron stars

2019 ◽  
Vol 55 (11) ◽  
Author(s):  
Domenico Logoteta ◽  
Isaac Vidaña ◽  
Ignazio Bombaci
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nucleon Nucleon ◽  
Effective Field ◽  
Many Body ◽  
Chiral Effective Field Theory ◽  
Hartree Fock ◽  
The Many ◽  
Three Body

Abstract.We study the effects of the nucleon-nucleon-lambda (NN$ \Lambda$Λ three-body force on neutron stars. In particular, we consider the NN$ \Lambda$Λ force recently derived by the Jülich-Bonn-Munich group within the framework of chiral effective field theory at next-to-next-to-leading order. This force, together with realistic nucleon-nucleon, nucleon-nucleon-nucleon and nucleon-hyperon interactions, is used to calculate the equation of state and the structure of neutron stars within the many-body non-relativistic Brueckner-Hartree-Fock approach. Our results show that the inclusion of the NN$ \Lambda$Λ force leads to an equation of state stiff enough such that the resulting neutron star maximum mass is compatible with the largest currently measured ( $ \sim 2 M_\odot$∼2M⊙ neutron star masses. Using a perturbative many-body approach we calculate also the separation energy of the $ \Lambda$Λ in some hypernuclei finding that the agreement with the experimental data improves for the heavier ones when the effect of the NN$ \Lambda$Λ force is taken into account.

scholarly journals Recent Progress in Neutron Star Theory

2000 ◽  
Vol 50 (1) ◽  
pp. 481-524 ◽  
Author(s):  
Henning Heiselberg ◽  
Vijay Pandharipande
Keyword(s):  
Phase Transitions ◽  
Neutron Star ◽  
Neutron Stars ◽  
Recent Progress ◽  
Nuclear Forces ◽  
Neutron Star Matter ◽  
Many Body ◽  
Kaon Condensation ◽  
Probable Effect ◽  
Body Techniques

▪ Abstract  We review recent progress in the theory of neutron stars and compare its predictions with the observational data on masses, radii, and temperatures. The theory of neutron stars made up of neutrons, protons, and leptons is discussed in detail along with recent models of nuclear forces and modern many-body techniques. The possibilities of pion and kaon condensation in dense neutron star matter are considered, as is the possible occurrence of strange hyperons and quark-matter drops in the stellar core. The structure of mixed-phase matter in neutron stars, as well as the probable effect of phase transitions on the spin down of pulsars, is also discussed.

scholarly journals Nuclear equation of state and neutron star cooling

2017 ◽  
Vol 26 (04) ◽  
pp. 1750015 ◽  
Author(s):  
Yeunhwan Lim ◽  
Chang Ho Hyun ◽  
Chang-Hwan Lee
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Thermal Evolution ◽  
Observation Data ◽  
Nuclear Equation Of State ◽  
The Core ◽  
Dense Nuclear Matter ◽  
Nuclear Models

In this paper, we investigate the cooling of neutron stars with relativistic and nonrelativistic models of dense nuclear matter. We focus on the effects of uncertainties originated from the nuclear models, the composition of elements in the envelope region, and the formation of superfluidity in the core and the crust of neutron stars. Discovery of [Formula: see text] neutron stars PSR J1614−2230 and PSR J0343[Formula: see text]0432 has triggered the revival of stiff nuclear equation of state at high densities. In the meantime, observation of a neutron star in Cassiopeia A for more than 10 years has provided us with very accurate data for the thermal evolution of neutron stars. Both mass and temperature of neutron stars depend critically on the equation of state of nuclear matter, so we first search for nuclear models that satisfy the constraints from mass and temperature simultaneously within a reasonable range. With selected models, we explore the effects of element composition in the envelope region, and the existence of superfluidity in the core and the crust of neutron stars. Due to uncertainty in the composition of particles in the envelope region, we obtain a range of cooling curves that can cover substantial region of observation data.

scholarly journals Constraints on the inner edge of neutron star crusts from relativistic nuclear energy density functionals

2019 ◽  
Vol 18 ◽  
pp. 107
Author(s):  
Ch. C. Moustakidis ◽  
T. Niksic ◽  
G. A. Lalazissis ◽  
D. Vretenar ◽  
P. Ring
Keyword(s):  
Neutron Star ◽  
Energy Density ◽  
Neutron Stars ◽  
Nuclear Energy ◽  
Liquid Core ◽  
Transition Density ◽  
Binding Energies ◽  
Density Functionals ◽  
The Core ◽  
Finite Nuclei

The transition density nt and pressure Pt at the inner edge between the liquid core and the solid crust of a neutron star are analyzed using the thermodynami- cal method and the framework of relativistic nuclear energy density functionals. Starting from a functional that has been carefully adjusted to experimental binding energies of finite nuclei, and varying the density dependence of the cor- responding symmetry energy within the limits determined by isovector prop- erties of finite nuclei, we estimate the constraints on the core-crust transition density and pressure of neutron stars: 0.086 fm−3 ≤ nt < 0.090 fm−3 and 0.3 MeV fm−3 < Pt ≤ 0.76 MeV fm−3 [1].

scholarly journals A hybrid model of Skyrme- and Brueckner-type interactions for neutron star matter

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Soonchul Choi ◽  
Myung-Ki Cheoun ◽  
K S Kim ◽  
Hungchong Kim ◽  
H Sagawa
Keyword(s):  
Neutron Star ◽  
Hybrid Model ◽  
Clear Understanding ◽  
Neutron Skin ◽  
Neutron Star Matter ◽  
Many Body ◽  
Hartree Fock ◽  
Nuclear Incompressibility ◽  
The Many ◽  
Many Body Interactions

Abstract We suggest a hybrid model for neutron star matter to discuss the hyperon puzzle inherent in the 2.0 M$_{\odot}$ of the neutron star. For the nucleon–nucleon ($NN$) interaction, we employ the Skyrme–Hartree–Fock approach based on various Skyrme interaction parameter sets, and take the Brueckner–Hartree–Fock approach for the interactions related to hyperons. For the many-body interactions including hyperons, we make use of the multi-pomeron-exchange model, whose parameters have been adjusted to the data deduced from various hypernuclei properties. For clear understanding of the physics in the hybrid model, we discuss fractional functions of related particles, symmetry energies, and chemical potentials in dense matter. Finally, we investigate the equations of state and mass–radius relation of neutron stars, and show that the hybrid model can properly describe the 2.0 M$_{\odot}$ neutron star mass data with the many-body interaction employed in the hybrid model. Recent tidal deformability data from the gravitational wave observation are also compared to our calculations, especially in terms of the neutron skin of $^{208}$Pb and nuclear incompressibility.

RELATIVISTIC ELECTRONS IN A ROTATING SPHERICAL MAGNETIC DIPOLE: LOCALIZED THREE-DIMENSIONAL STATES

1999 ◽  
Vol 08 (02) ◽  
pp. 251-270 ◽  
Author(s):  
JAMES M. GELB ◽  
KAUNDINYA S. GOPINATH ◽  
DALLAS C. KENNEDY
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Dipole ◽  
Fermi Energy ◽  
Three Dimensional ◽  
Relativistic Electrons ◽  
Many Body ◽  
First Case ◽  
The Many ◽  
Body Case

Paralleling a previous paper, we examine single- and many-body states of relativistic electrons in an intense, rotating magnetic dipole field. Single-body orbitals are derived semiclassically and then applied to the many-body case via the Thomas-Fermi approximation. The many-body case is reminiscent of the quantum Hall state. Electrons in a realistic neutron star crust are considered with both fixed density profiles and constant Fermi energy. In the first case, applicable to young neutron star crusts, the varying magnetic field and relativistic Coriolis correction lead to a varying Fermi energy and macroscopic currents. In the second, relevant to older crusts, the electron density is redistributed by the magnetic field.

scholarly journals Neutron star equation of state and uncertainty on the radius determination

2017 ◽  
Vol 13 (S337) ◽  
pp. 225-228
Author(s):  
Morgane Fortin
Keyword(s):  
Experimental Data ◽  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Model ◽  
Large Collection ◽  
X Ray ◽  
The Core ◽  
Simultaneous Measurements ◽  
New Generation

AbstractSimultaneous measurements of the radius and mass of neutron stars (NSs) are expected from the new generation of X-ray telescopes, potentially constraining the NS equation of state (EoS). However using ‘non-unified’ EoSs with the ones for the core and the crust not based on the same nuclear model can introduce an uncertainty on the radius as large as the precision expected from these instruments. I present two solutions to this problem: a large collection of unified EoSs and an approximate and yet precise approach that, with no need of a crust EoS, provides the relation between the NS mass and radius. I discuss correlations between the NS radius and nuclear parameters, possibly allowing to constrain the NS radius with experiments on Earth. Finally, I show that in spite of the observation of massive NSs, one can not exclude that hyperons appear at high densities in NSs due to the scarcity of the available experimental data.

scholarly journals Incommensurate Crystallization of Neutron Matter in Neutron Stars

2020 ◽  
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Specific Heat ◽  
Inner Core ◽  
Surface Region ◽  
Outer Core ◽  
Neutron Matter ◽  
High Mass ◽  
The Core ◽  
Gravitational Stress

The composition of the neutron stars from its surface region, outer-core, inner-core, and to its center is still being investigated. One can only surmise on the properties of neutron stars from the spectroscopic data that may be available from time to time. A few models have suggested that the matter at the surface region of the neutron star is composed of atomic nuclei that get crushed under extremely large pressure and gravitational stress, and this leads to the creation of solid lattice with a sea of electrons, and perhaps some protons, flowing through the gaps between them. Nuclei with high mass numbers, such as ferrous, gold, platinum, uranium, may exist in the surface region or in the outer-core region. It is found that the structure of the neutron star changes very much as one goes from the surface to the core of the neutron star. The surface region is extremely hard and very smooth. Surface irregularities are hardly of the order of 5 mm, whereas the interior of the neutron star may be superfluid and composed of neutron-degenerate matter. However, the neutron star is highly compact crystalline systems, and in terrestrial materials under pressure, many examples of incommensurate phase transitions have been discovered. Consequently, the properties of incommensurate crystalline neutron star have been studied. The composition of the neutron stars in the super dense state remains uncertain in the core of the neutron star. One model describes the core as superfluid neutron-degenerate matter, mostly, composed of neutrons , and a small percentage of protons and electrons More exotic forms of matter are possible, including degenerate strange matter. It could also be incommensurate crystalline neutron matter that could be BCC or HCP. Using principles of quantum statistical mechanics, the specific heat and entropy of the incommensurate crystalline neutron star has been calculated assuming that the temperature of the star may vary between to . Two values for the temperature T that have been arbitrarily chosen for which the calculations have been done are and . The values of specific heat and entropy decrease as the temperature increases, and also, their magnitudes are very small. This is in line with the second law of thermodynamics.

scholarly journals Towards an Empirical Unified Crust–Core Description of Neutron Stars

2017 ◽  
Vol 34 ◽  
Author(s):  
Debarati Chatterjee ◽  
Francesca Gulminelli
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Density Functional ◽  
Low Density ◽  
X Ray ◽  
The Core ◽  
Neutron Star Crust ◽  
Functional Scheme ◽  
Core Description ◽  
Density Regime

AbstractUnderstanding the properties of the crust and the core as well as its interface is essential for accurate astrophysical modelling of phenomena such as glitches, X-ray bursts or oscillations in neutron stars. To study the crust–core properties, it is crucial to develop a unified and consistent scheme to describe both the clusterised matter in the crust and homogeneous matter in the core. The low density regime in the neutron star crust is accessible to terrestrial nuclear experiments. In order to develop a consistent description of the crust and the core of neutron stars within the same formalism, we use a density functional scheme, with the model coefficients in homogeneous matter related directly to empirical nuclear observables. In this work, we extend this scheme to non-homogeneous matter to describe nuclei in the crust. We then test this scheme against nuclear observables.

scholarly journals Improved Versions of Fielek Model for BCC Transition Metals

1980 ◽  
Vol 35 (9) ◽  
pp. 920-923 ◽  
Author(s):  
R. N. Khanna ◽  
R. P. S. Rathore
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Dispersion Relations ◽  
Many Body ◽  
Body Type ◽  
Equilibrium Conditions ◽  
The Third ◽  
The Core ◽  
The Many ◽  
Experimental Findings

Abstract Three improved versions of the Fielek Model are developed and discussed. The first model uses a modified Bhatia scheme for the volume interaction in place of the Krebs scheme. The second and third model assumes the core-core couplings to be central pairwise effective upto first neighbours only. The second model describes the d-shell-d-shell interaction on the same lines as those adopted for core-core interactions, while the third model assumes these interactions to be of the many body type. Suitable equilibrium conditions for the second and the third model are developed. These improved versions are employed to derive dispersion relations in tantalum. Comparison of these relations with-each other and also with the experimental findings leads to some important conclusions regarding the nature and range of the interactions coupling the various constituents of a bcc transition metal like tantalum.

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