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 Equation of state of dense nuclear matter and neutron star structure from nuclear chiral interactions

2018 ◽  
Vol 609 ◽  
pp. A128 ◽  
Author(s):  
Ignazio Bombaci ◽  
Domenico Logoteta
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Symmetric Nuclear Matter ◽  
Heavy Nuclei ◽  
Hartree Fock ◽  
Binary Neutron Star ◽  
Dense Nuclear Matter ◽  
Three Body

Aims. We report a new microscopic equation of state (EOS) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and β-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear interactions derived in the framework of chiral perturbation theory (ChPT) and including the Δ(1232) isobar intermediate state. This EOS is provided in tabular form and in parametrized form ready for use in numerical general relativity simulations of binary neutron star merging. Here we use our new EOS for β-stable nuclear matter to compute various structural properties of non-rotating neutron stars. Methods. The EOS is derived using the Brueckner–Bethe–Goldstone quantum many-body theory in the Brueckner–Hartree–Fock approximation. Neutron star properties are next computed solving numerically the Tolman–Oppenheimer–Volkov structure equations. Results. Our EOS models are able to reproduce the empirical saturation point of symmetric nuclear matter, the symmetry energy Esym, and its slope parameter L at the empirical saturation density n0. In addition, our EOS models are compatible with experimental data from collisions between heavy nuclei at energies ranging from a few tens of MeV up to several hundreds of MeV per nucleon. These experiments provide a selective test for constraining the nuclear EOS up to ~4n0. Our EOS models are consistent with present measured neutron star masses and particularly with the mass M = 2.01 ± 0.04 M⊙ of the neutron stars in PSR J0348+0432.

scholarly journals What can neutron stars reveal about the equation of state of dense matter?

2020 ◽  
Vol 235 ◽  
pp. 07002
Author(s):  
Ingo Tews
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Physics ◽  
Nuclear Astrophysics ◽  
Dense Matter ◽  
Effective Field ◽  
Chiral Effective Field Theory ◽  
Astrophysical Objects ◽  
R Process

Neutron stars are astrophysical objects of extremes, reaching the highest densities we can observe in the cosmos, and probing matter under conditions that cannot be recreated in terrestrial experiments. In August 2017, the first neutron-star merger has been observed, which provided compelling evidence that these events are an important site for r-process nucleosynthesis. Furthermore, the gravitational-wave signal of such events might shed light upon the nature of strongly interacting matter in the neutron-star core. To understand these remarkable events, reliable nuclear physics input is essential. In this contribution, I explain how to use chiral effective field theory and advanced many-body methods to provide a consistent and systematic approach to strongly inter- acting systems from nuclei to neutron stars with controlled theoretical uncertainties. I will discuss recent results for the equation of state relevant for the nuclear astrophysics of neutron stars and neutron-star mergers.

scholarly journals 1S0 Pairing Gaps, Chemical Potentials and Entrainment Matrix in Superfluid Neutron-Star Cores for the Brussels–Montreal Functionals

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 470
Author(s):  
Valentin Allard ◽  
Nicolas Chamel
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Physical Meaning ◽  
Outer Core ◽  
Time Dependent ◽  
Hartree Fock ◽  
Chemical Potentials ◽  
Bogoliubov Equations ◽  
Flow Velocities

Temperature and velocity-dependent 1S0 pairing gaps, chemical potentials and entrainment matrix in dense homogeneous neutron–proton superfluid mixtures constituting the outer core of neutron stars, are determined fully self-consistently by solving numerically the time-dependent Hartree–Fock–Bogoliubov equations over the whole range of temperatures and flow velocities for which superfluidity can exist. Calculations have been made for npeμ in beta-equilibrium using the Brussels–Montreal functional BSk24. The accuracy of various approximations is assessed and the physical meaning of the different velocities and momentum densities appearing in the theory is clarified. Together with the unified equation of state published earlier, the present results provide consistent microscopic inputs for modeling superfluid neutron-star cores.

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.

THE BETHE–BRUECKNER–GOLDTONE THEORY OF THE NUCLEAR EQUATION OF STATE AND NEUTRON STARS

2003 ◽  
Vol 17 (28) ◽  
pp. 5127-5137 ◽  
Author(s):  
M. BALDO ◽  
G. F. BURGIO
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Gluon Plasma ◽  
Many Body ◽  
Static Properties ◽  
Many Body Theory ◽  
Nuclear Equation Of State ◽  
Pure Neutron Matter ◽  
Particle Potential ◽  
Three Body

The microscopic many-body theory of the Nuclear Equation of State is discussed in the framework of the Bethe–Brueckner–Goldstone method. The expansion is extended up to the three hole-line diagrams contribution. The Brueckner equation for the two-body G-matrix and the Bethe–Fadeev equation for the three-body scattering matrix are solved both for the gap and continuous choices of the single particle potential. For symmetric and pure neutron matter strong evidence of convergence in the expansion is found. Once three-body forces are introduced, the phenomenological saturation point is reproduced. In order to study neutron stars static properties, the theory is extended to include strangeness, and the possible quark-gluon plasma component is described in the simplified MIT bag model. The results for the mass and radius of neutron stars are briefly discussed.

scholarly journals Chiral Effective Field Theory and the High-Density Nuclear Equation of State

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
C. Drischler ◽  
J.W. Holt ◽  
C. Wellenhofer
Keyword(s):  
Field Theory ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Effective Field Theory ◽  
Effective Field ◽  
High Density ◽  
Chiral Effective Field Theory ◽  
Nuclear Equation Of State ◽  
Density Regime

Born in the aftermath of core-collapse supernovae, neutron stars contain matter under extraordinary conditions of density and temperature that are difficult to reproduce in the laboratory. In recent years, neutron star observations have begun to yield novel insights into the nature of strongly interacting matter in the high-density regime where current theoretical models are challenged. At the same time, chiral effective field theory has developed into a powerful framework to study nuclear matter properties with quantified uncertainties in the moderate-density regime for modeling neutron stars. In this article, we review recent developments in chiral effective field theory and focus on many-body perturbation theory as a computationally efficient tool for calculating the properties of hot and dense nuclear matter. We also demonstrate how effective field theory enables statistically meaningful comparisons among nuclear theory predictions, nuclear experiments, and observational constraints on the nuclear equation of state. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 71 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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.

scholarly journals Cooling of hybrid neutron stars with microscopic equations of state

2020 ◽  
Vol 498 (1) ◽  
pp. 344-354 ◽  
Author(s):  
J-B Wei ◽  
G F Burgio ◽  
H-J Schulze ◽  
D Zappalà
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Equations Of State ◽  
P Wave ◽  
Cooling Curves ◽  
Hartree Fock ◽  
Nuclear Equation Of State ◽  
Neutron Star Cooling ◽  
Quark Models

ABSTRACT We model the cooling of hybrid neutron stars combining a microscopic nuclear equation of state in the Brueckner–Hartree–Fock approach with different quark models. We then analyse the neutron star cooling curves predicted by the different models and single out the preferred ones. We find that the possibility of neutron p-wave pairing can be excluded in our scenario.

scholarly journals Effects of chiral effective field theory equation of state on binary neutron star mergers

2018 ◽  
Vol 98 (4) ◽  
Author(s):  
Andrea Endrizzi ◽  
Domenico Logoteta ◽  
Bruno Giacomazzo ◽  
Ignazio Bombaci ◽  
Wolfgang Kastaun ◽  
...  
Keyword(s):  
Field Theory ◽  
Neutron Star ◽  
Equation Of State ◽  
Effective Field Theory ◽  
Effective Field ◽  
Chiral Effective Field Theory ◽  
Binary Neutron Star ◽  
Theory Equation

Neutron star properties from optimised chiral nuclear interactions

2018 ◽  
Vol 35 ◽  
Author(s):  
D. Logoteta ◽  
I. Bombaci
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Nuclear Interaction ◽  
Binding Energies ◽  
Leading Order ◽  
Nuclear Forces ◽  
Hartree Fock ◽  
First Case ◽  
Three Body

AbstractWe adopt two- and three-body nuclear forces derived at the next-to-next-to-leading-order in the framework of effective chiral perturbation theory to calculate the equation of state of β-stable neutron star matter using the Brueckner–Hartree–Fock many-body approach. We use the recent optimized chiral two-body nuclear interaction at next-to-next-to-leading-order derived by Ekström et al. and two different parametrizations of the three-body next-to-next-to-leading-order interaction: the first one is fixed to reproduce the saturation point of symmetric nuclear matter while the second one is fixed to reproduce the binding energies of light atomic nuclei. We show that in the second case the properties of nuclear matter are not well determined whereas in the first case various empirical nuclear matter properties around the saturation density are well reproduced. We finally calculate various neutron star properties and in particular the mass-radius and mass-central density relations. We find that the adopted interactions based on a fully microscopic framework, are able to provide an equation of state which is consistent with the present data of measured neutron star masses.

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