scholarly journals Quark matter symmetry energy effect on equation of state for neutron stars

2019 ◽  
Author(s):  
Xuhao Wu ◽  
Akira Ohnishi ◽  
Hong Shen
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Quark Matter ◽  
Energy Effect

scholarly journals Constraints on EOS from finite nuclei, heavy ion collisions and neutron stars

2020 ◽  
Vol 15 ◽  
pp. 196
Author(s):  
T. Gaitanos ◽  
G. Ferini ◽  
M. Colonna ◽  
M. Di Toro ◽  
G. A. Lalazissis ◽  
...  
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Ground State ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Intermediate Energy ◽  
Ion Collisions ◽  
Finite Nuclei ◽  
Asymmetric Matter

We present several possibilities offered by nuclear structure, the dynamics of intermediate energy heavy ion collisions and neutron stars to investigate the nuclear matter equation of state (EoS) beyond the ground state. In particular the high density nuclear EoS of asymmetric matter, i.e. the symmetry energy, is discussed.

NEW ASPECTS ON GRAVITATIONAL WAVE EMISSION BY NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1293-1296 ◽  
Author(s):  
GUILHERME F. MARRANGHELLO ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
JOSÉ A. de FREITAS PACHECO ◽  
MANFRED DILLIG ◽  
HÉLIO T. COELHO
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Quark Matter ◽  
Inner Core ◽  
Compact Objects ◽  
Wave Emission

We discuss, in this work, new aspects related to the emission of gravitational waves by neutron stars, which undergo a phase transition, from nuclear to quark matter, in its inner core. Such a phase transition would liberate around 1052–53 erg of energy in the form of gravitational waves which, if detected, may shed some light in the structure of these compact objects and provide new insights on the equation of state of nuclear matter.

scholarly journals Possibility of rapid neutron star cooling with a realistic equation of state

2019 ◽  
Vol 2019 (11) ◽  
Author(s):  
Akira Dohi ◽  
Ken’ichiro Nakazato ◽  
Masa-aki Hashimoto ◽  
Matsuo Yasuhide ◽  
Tsuneo Noda
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Surface Composition ◽  
Thermal Evolution ◽  
Small Radius ◽  
Neutron Star Cooling ◽  
Fast Cooling ◽  
Urca Process

Abstract Whether fast cooling processes occur or not is crucial for the thermal evolution of neutron stars. In particular, the threshold of the direct Urca process, which is one of the fast cooling processes, is determined by the interior proton fraction $Y_p$, or the nuclear symmetry energy. Since recent observations indicate the small radius of neutron stars, a low value is preferred for the symmetry energy. In this study, simulations of neutron star cooling are performed adopting three models for the equation of state (EoS): Togashi, Shen, and LS220 EoSs. The Togashi EoS has been recently constructed with realistic nuclear potentials under finite temperature, and found to account for the small radius of neutron stars. As a result, we find that, since the direct Urca process is forbidden, the neutron star cooling is slow with use of the Togashi EoS. This is because the symmetry energy of Togashi EoS is lower than those of other EoSs. Hence, in order to account for observed age and surface temperature of isolated neutron stars with the use of the Togashi EoS, other fast cooling processes are needed regardless of the surface composition.

scholarly journals Rotation-Driven Phase Transitions in the Cores of Pulsars

2017 ◽  
Vol 45 ◽  
pp. 1760035
Author(s):  
Richard D. Mellinger ◽  
William Spinella ◽  
Fridolin Weber ◽  
Gustavo A. Contrera ◽  
Milva Orsaria
Keyword(s):  
Phase Transitions ◽  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quark Matter ◽  
Nuclear Data ◽  
Particle Composition ◽  
Nuclear Equation Of State ◽  
The Impact ◽  
Gravitational Compression

In this paper, we discuss the impact of rotation on the particle composition of rotating neutron stars (pulsars). Particular emphasis is put on the formation of quark matter during stellar spin-down, driven by continuous gravitational compression. Our study is based on modern models for the nuclear equation of state whose parameters are tightly constrained by nuclear data, neutron star masses, and the latest estimates of neutron star radii.

EFFECTS OF THE NUCLEAR SYMMETRY ENERGY ON GRAVITATIONAL WAVES FROM THE AXIAL W-MODES OF ISOLATED NEUTRON STARS

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1712-1719
Author(s):  
DE-HUA WEN ◽  
BAO-AN LI ◽  
PLAMEN G. KRASTEV
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Symmetry Energy ◽  
Laboratory Data ◽  
High Density ◽  
Nuclear Symmetry Energy ◽  
Nuclear Equation Of State ◽  
Eigen Frequencies ◽  
Density Behavior

The frequencies and damping times of the axial w-mode oscillations of neutron stars are investigated using a nuclear equation of state (EOS) partially constrained by the available terrestrial laboratory data. It is found that the nuclear symmetry energy E sym (ρ), especially its high density behavior, plays an important role in determining both the eigen-frequencies and the damping times of these oscillations.

scholarly journals KIDS Energy Density Functional and Mass–Radius Relation of Neutron Stars

2019 ◽  
Vol 26 ◽  
pp. 112
Author(s):  
G. Ahn ◽  
P. Papakonstantinou
Keyword(s):  
Equation Of State ◽  
Energy Density ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Density Functional ◽  
Nuclear Symmetry Energy ◽  
Unified Framework ◽  
Energy Density Functional ◽  
Nuclear Equation Of State ◽  
Derivatives Of

Many efforts are made to determine the nuclear equation of state which governs the properties and evolution of neutron stars. Especially important is to constrain the parameters of the nuclear symmetry energy. In those efforts, nuclear energy density functional (EDF) theory has been a very useful tool, as it provides a unified framework for the description both of nuclei, which can be studied on Earth, and of infinite matter and its nuclear equation of state, which is a necessary input in the modelling of neutron stars. In the present study, a new nuclear EDF, the KIDS functional, is explored with a focus on the nuclear symmetry energy. The form of the functional allows us to vary at will the poorly constrained high-order derivatives of the symmetry energy and examine how the maximum possible mass of a neutron star is affected. Some tentative constraints on the skewness are presented, which will help guide further refinements. It is noteworthy that the pressure of neutron-rich matter is found strongly affected by skewness variations, both at low and high densities.

scholarly journals Nuclear equation of state constraints from tidal deformability of neutron stars

2019 ◽  
Vol 21 ◽  
pp. 44
Author(s):  
Ch. C. Moustakidis
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
State Constraints ◽  
Equations Of State ◽  
Recent Observation ◽  
Nuclear Symmetry Energy ◽  
Nuclear Equation Of State ◽  
Theoretical Predictions

We study the effect of nuclear equation of state on the tidal polarizability of neutron stars. The predicted equations of state for the β-stable nuclear matter are parameterized by varying the slope L of the symmetry energy at saturation density on the interval 65 MeV≤L≤115 MeV. The effects of the density dependence of the nuclear symmetry energy on the neutron star tidal polarizability are presented and analyzed. A comparison of theoretical predictions with the recent observation predictions is also performed and analyzed.

scholarly journals Simulating Binary Neutron Stars with Hybrid Equation of States: Gravitational Waves, Electromagnetic Signatures and Challenges for Numerical Relativity

Particles ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 365-384 ◽  
Author(s):  
Henrique Gieg ◽  
Tim Dietrich ◽  
Maximiliano Ujevic
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Strange Quark ◽  
Numerical Relativity ◽  
Strange Quark Matter ◽  
Strong Phase ◽  
Equation Of States

The gravitational wave and electromagnetic signatures connected to the merger of two neutron stars allow us to test the nature of matter at supranuclear densities. Since the Equation of State governing the interior of neutron stars is only loosely constrained, there is even the possibility that strange quark matter exists inside the core of neutron stars. We investigate how strange quark matter cores affect the binary neutron star coalescence by performing numerical relativity simulations. Interestingly, the strong phase transition can cause a reduction of the convergence order of the numerical schemes to first order if the numerical resolution is not high enough. Therefore, an additional challenge is added in producing high-quality gravitational wave templates for Equation of States with a strong phase transition. Focusing on one particular configuration of an equal mass configuration consistent with GW170817, we compute and discuss the associated gravitational wave signal and some of the electromagnetic counterparts connected to the merger of the two stars. We find that existing waveform approximants employed for the analysis of GW170817 allow describing this kind of systems within the numerical uncertainties, which, however, are several times larger than for pure hadronic Equation of States, which means that even higher resolutions have been employed for an accurate gravitational wave model comparison. We also show that for the chosen Equation of State, quasi-universal relations describing the gravitational wave emission after the moment of merger seem to hold and that the electromagnetic signatures connected to our chosen setup would not be bright enough to explain the kilonova associated to GW170817.

scholarly journals TRANSITION DENSITY AND PRESSURE AT THE INNER EDGE OF NEUTRON STAR CRUSTS

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1705-1711
Author(s):  
JUN XU ◽  
CHE MING KO ◽  
LIE-WEN CHEN ◽  
BAO-AN LI ◽  
HONG-RU MA
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Transition Density ◽  
Heavy Ion ◽  
Intermediate Energy ◽  
Nuclear Symmetry Energy ◽  
Parabolic Approximation ◽  
Ion Collisions

Using the nuclear symmetry energy that has been recently constrained by the isospin diffusion data in intermediate-energy heavy ion collisions, we have studied the transition density and pressure at the inner edge of neutron star crusts, and they are found to be 0.040 fm -3 ≤ ρt ≤ 0.065 fm -3 and 0.01 MeV / fm 3 ≤ Pt ≤ 0.26 MeV / fm 3, respectively, in both the dynamical and thermodynamical approaches. We have also found that the widely used parabolic approximation to the equation of state of asymmetric nuclear matter gives significantly higher values of core-crust transition density and pressure, especially for stiff symmetry energies. With these newly determined transition density and pressure, we have obtained an improved relation between the mass and radius of neutron stars.

QUARK MATTER IN NEUTRON STARS: AN APERÇU

2006 ◽  
Vol 21 (26) ◽  
pp. 1965-1979 ◽  
Author(s):  
PRASHANTH JAIKUMAR ◽  
SANJAY REDDY ◽  
ANDREW W. STEINER
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quark Matter ◽  
Finite Size ◽  
Coulomb Energy ◽  
Quark Stars ◽  
Dense Quark Matter ◽  
Intermediate Fraction ◽  
State Of Matter

The existence of deconfined quark matter in the superdense interior of neutron stars is a key question that has drawn considerable attention over the past few decades. Quark matter can comprise an arbitrary fraction of the star, from 0 for a pure neutron star to 1 for a pure quark star, depending on the equation of state of matter at high density. From an astrophysical viewpoint, these two extreme cases are generally expected to manifest different observational signatures. An intermediate fraction implies a hybrid star, where the interior consists of mixed or homogeneous phases of quark and nuclear matter, depending on surface and Coulomb energy costs, as well as other finite size and screening effects. In this review, we discuss what we can deduce about quark matter in neutron stars in light of recent exciting developments in neutron star observations. We state the theoretical ideas underlying the equation of state of dense quark matter, including color superconducting quark matter. We also highlight recent advances stemming from re-examination of an old paradigm for the surface structure of quark stars and discuss possible evolutionary scenarios from neutron stars to quark stars, with emphasis on astrophysical observations.

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