NEUTRON STARS AND THE COHERENT NUCLEAR INTERACTION

1995 ◽  
Vol 04 (04) ◽  
pp. 531-548 ◽  
Author(s):  
E. DEL GIUDICE ◽  
R. MELE ◽  
G. PREPARATA ◽  
C. GUALDI ◽  
G. MANGANO ◽  
...  
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Interaction ◽  
Central Density ◽  
Maximum Mass ◽  
Minimum Period ◽  
Novel Approach ◽  
Coherent Interaction ◽  
New Equation ◽  
The Masses

In the framework of a novel approach to the dynamics of nuclei and large collections of nucleons, which fully exploits the coherent interaction among π’s, nucleons and Δ’s, we derive a new equation of state for neutronic matter. By introducing it in the Tolman-Oppenheimer-Volkof equations we derive the masses and radii of neutron stars as a function of the central density. We obtain a maximum mass Mmax≃2.7 Mʘ and a minimum period of rotation Tmin=0.8 msec.

scholarly journals The Effects of Nuclear Forces on the Maximum Mass Limit of Neutron Stars

1971 ◽  
Vol 46 ◽  
pp. 352-355
Author(s):  
Sachiko Tsuruta
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Interaction ◽  
Maximum Mass ◽  
Nuclear Forces ◽  
Mass Limit ◽  
Improved Model

The original models of neutron stars must be improved by including effects of nuclear interaction. This paper compares the models reached by various groups, and presents an improved model by the Kyoto group. The maximum mass varies between 0.2 M⊙ and 3 M⊙ in the various models. The Vγ model is recommended for use in the absence of further information on the equation of state at high densities.

scholarly journals A lower bound on the maximum mass if the secondary in GW190814 was once a rapidly spinning neutron star

2020 ◽  
Vol 499 (1) ◽  
pp. L82-L86 ◽  
Author(s):  
Elias R Most ◽  
L Jens Papenfort ◽  
Lukas R Weih ◽  
Luciano Rezzolla
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Equation Of State ◽  
Lower Bound ◽  
Neutron Stars ◽  
Compact Objects ◽  
Maximum Mass ◽  
Secondary Neutron ◽  
Massive Neutron Star ◽  
The Masses

ABSTRACT The recent detection of GW190814 featured the merger of a binary with a primary having a mass of $\sim 23\, \mathrm{ M}_{\odot }$ and a secondary with a mass of $\sim 2.6\, \mathrm{ M}_{\odot }$. While the primary was most likely a black hole, the secondary could be interpreted as either the lightest black hole or the most massive neutron star ever observed, but also as the indication of a novel class of exotic compact objects. We here argue that although the secondary in GW190814 is most likely a black hole at merger, it needs not be an ab-initio black hole nor an exotic object. Rather, based on our current understanding of the nuclear-matter equation of state, it can be a rapidly rotating neutron star that collapsed to a rotating black hole at some point before merger. Using universal relations connecting the masses and spins of uniformly rotating neutron stars, we estimate the spin, $0.49_{-0.05}^{+0.08} \lesssim \chi \lesssim 0.68_{-0.05}^{+0.11}$, of the secondary – a quantity not constrained so far by the detection – and a novel strict lower bound on the maximum mass, $M_{_{\mathrm{TOV}}}\gt 2.08^{+0.04}_{-0.04}\, \, \mathrm{ M}_{\odot }$ and an optimal bound of $M_{_{\mathrm{TOV}}}\gt 2.15^{+0.04}_{-0.04}\, \, \mathrm{ M}_{\odot }$, of non-rotating neutron stars, consistent with recent observations of a very massive pulsar. The new lower bound also remains valid even in the less likely scenario in which the secondary neutron star never collapsed to a black hole.

scholarly journals Pulsars in Globular Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 291-300 ◽  
Author(s):  
Scott M. Ransom
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Globular Clusters ◽  
Main Sequence ◽  
Galactic Disk ◽  
Nuclear Density ◽  
Millisecond Pulsars ◽  
Eccentric Orbits ◽  
The Masses ◽  
Current Record

AbstractGlobular clusters produce orders of magnitude more millisecond pulsars per unit mass than the Galactic disk. Since the first cluster pulsar was uncovered 20 years ago, at least 138 have been identified – most of which are binary millisecond pulsars. Because their origins involve stellar encounters, many of the systems are exotic objects that would never be observed in the Galactic disk. Examples include pulsar-main sequence binaries, extremely rapid rotators (including the current record holder), and millisecond pulsars in highly eccentric orbits. These systems are allowing new probes of the interstellar medium, the equation of state of material at supra-nuclear density, the masses of neutron stars, and globular cluster dynamics.

scholarly journals Astrophysical implications of neutron star inspiral and coalescence

2020 ◽  
Vol 29 (11) ◽  
pp. 2041015
Author(s):  
John L. Friedman ◽  
Nikolaos Stergioulas
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Maximum Mass ◽  
X Ray ◽  
Spectral Bands ◽  
Heaviest Elements ◽  
X Ray Binaries

The first inspiral of two neutron stars observed in gravitational waves was remarkably close, allowing the kind of simultaneous gravitational wave and electromagnetic observation that had not been expected for several years. Their merger, followed by a gamma-ray burst and a kilonova, was observed across the spectral bands of electromagnetic telescopes. These GW and electromagnetic observations have led to dramatic advances in understanding short gamma-ray bursts; determining the origin of the heaviest elements; and determining the maximum mass of neutron stars. From the imprint of tides on the gravitational waveforms and from observations of X-ray binaries, one can extract the radius and deformability of inspiraling neutron stars. Together, the radius, maximum mass, and causality constrain the neutron-star equation of state, and future constraints can come from observations of post-merger oscillations. We selectively review these results, filling in some of the physics with derivations and estimates.

Effect of the equation of state on the maximum mass of differentially rotating neutron stars

2016 ◽  
Vol 463 (3) ◽  
pp. 2667-2679 ◽  
Author(s):  
A. M. Studzińska ◽  
M. Kucaba ◽  
D. Gondek-Rosińska ◽  
L. Villain ◽  
M. Ansorg
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Maximum Mass

HADRON-QUARK PHASE TRANSITION AND ANTIKAON CONDENSATION IN NEUTRON STARS

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2481-2484
Author(s):  
H. SHEN ◽  
F. YANG ◽  
P. YUE
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maximum Mass ◽  
Relativistic Mean Field ◽  
The Core ◽  
Quark Phase

We study the hadron-quark phase transition and antikaon condensation which may occur in the core of massive neutron stars. The relativistic mean field theory is used to describe the hadronic phase, while the Nambu-Jona-Lasinio model is adopted for the quark phase. We find that the hadron-quark phase transition is very sensitive to the models used. The appearance of deconfined quark matter and antikaon condensation can soften the equation of state at high density and lower the maximum mass of neutron stars.

scholarly journals Unified Equation of State for Neutron Stars Based on the Gogny Interaction

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1613
Author(s):  
Xavier Viñas ◽  
Claudia Gonzalez-Boquera ◽  
Mario Centelles ◽  
Chiranjib Mondal ◽  
Luis M. Robledo
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Density Functional ◽  
Mean Field ◽  
Nuclear Interaction ◽  
Energy Density Functional ◽  
Hartree Fock ◽  
The Moment ◽  
Finite Nuclei ◽  
Pairing Field

The effective Gogny interactions of the D1 family were established by D. Gogny more than forty years ago with the aim to describe simultaneously the mean field and the pairing field corresponding to the nuclear interaction. The most popular Gogny parametrizations, namely D1S, D1N and D1M, describe accurately the ground-state properties of spherical and deformed finite nuclei all across the mass table obtained with Hartree–Fock–Bogoliubov (HFB) calculations. However, these forces produce a rather soft equation of state (EoS) in neutron matter, which leads to predict maximum masses of neutron stars well below the observed value of two solar masses. To remove this limitation, we built new Gogny parametrizations by modifying the density dependence of the symmetry energy predicted by the force in such a way that they can be applied to the neutron star domain and can also reproduce the properties of finite nuclei as good as their predecessors. These new parametrizations allow us to obtain stiffer EoS’s based on the Gogny interactions, which predict maximum masses of neutron stars around two solar masses. Moreover, other global properties of the star, such as the moment of inertia and the tidal deformability, are in harmony with those obtained with other well tested EoSs based on the SLy4 Skyrme force or the Barcelona–Catania–Paris–Madrid (BCPM) energy density functional. Properties of the core-crust transition predicted by these Gogny EoSs are also analyzed. Using these new Gogny forces, the EoS in the inner crust is obtained with the Wigner–Seitz approximation in the Variational Wigner–Kirkwood approach along with the Strutinsky integral method, which allows one to estimate in a perturbative way the proton shell and pairing corrections. For the outer crust, the EoS is determined basically by the nuclear masses, which are taken from the experiments, wherever they are available, or by HFB calculations performed with these new forces if the experimental masses are not known.

scholarly journals MAXIMUM MASS OF A CLASS OF COLD COMPACT STARS

2006 ◽  
Vol 15 (03) ◽  
pp. 405-418 ◽  
Author(s):  
R. SHARMA ◽  
S. KARMAKAR ◽  
S. MUKHERJEE
Keyword(s):  
Equation Of State ◽  
Boundary Conditions ◽  
Prior Knowledge ◽  
Surface Density ◽  
Equations Of State ◽  
Compact Stars ◽  
Central Density ◽  
Maximum Mass ◽  
Simple Method ◽  
Tov Equation

We calculate the maximum mass of the class of compact stars described by the Vaidya–Tikekar27 model. The model permits a simple method of systematically fixing bounds on the maximum possible mass of cold compact stars with a given value of radius or central density or surface density. The relevant equations of state are also determined. Although simple, the model is capable of describing the general features of the recently observed very compact stars. For the calculation, no prior knowledge of the equation of state (EOS) is required. This is in contrast to earlier calculations for maximum mass which were done by choosing first the relevant EOSs and using those to solve the TOV equation with appropriate boundary conditions. The bounds obtained by us are comparable and, in some cases, more restrictive than the earlier results.

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.

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