Effects of the Symmetry Energy and its Slope on Neutron Star Properties

In this work, we study the influence of the symmetry energy and its slope on three major properties of neutron stars: the maximum mass, the radii of the canonical 1.4 M _⊙ and the minimum mass that enables the direct Urca effect. We utilize four parametrizations of the relativistic quantum hadrodynamics and vary the symmetry energy within accepted values. We see that although the maximum mass is almost independent of it, the radius of the canonical 1.4M _⊙ and the mass that enables the direct Urca effect is strongly correlated with the symmetry energy and its slope. Also, since we expect that the radius grows with the slope, a theoretical limit arises when we increase this quantity above certain values.     

Neutron Resonances in Few-Body Systems and the EOS of Neutron Star Crust

The effective interactions formed by neutron rescattering between the nuclei fixed in nodes of the crystalline lattice of neutron star crusts have been considered. In the case of two-body resonances in neutron–nucleus subsystems new neutron resonances of few-body nature come into existence in the overdense crystal under certain conditions. The energies and widths of new resonances get additional dependence on the lattice parameters. The effective interactions result in nonlinear correction to the equation of state determined by the balance of gravitational, Coulomb and nuclear resonance forces. This leads to resonant oscillations of density in the accordant layers of crusts that are accompanied by oscillations of gamma radiation. The phenomena may clarify some processes connected with few-body neutron resonances in neutron star crusts, that have influence on the microstructure of pulsar impulses.     

Neutron Skin Thickness of Nuclei and Effective Nucleon-Nucleon Interactions

The Skyrme energy density functional is applied to study the ground state properties of a series of finite nuclei. The charge rms radii, neutron rms radii, and the neutron skin thickness for some nuclei are calculated and compared with the experimental data. The constraint on the effective interactions, especially, the density dependence of the isospin-dependent. part of Skyrme interactions is extracted by the data of neutron skin thicknesses of ^208Pb and isotopes of Sn.     

Neutron Star Matter and Baryonic Interactions

Physics of Atomic Nuclei - The properties of neutron-star matter up to the appearance of hyperons are calculated with the aid of Skyrme potentials. The conditions for the appearance of Λ...     

Neutron Star Matter Including Delta Isobars

In this paper a new phase structure of neutron star matter including nucleons and delta isobars is presented.Particle fractions populated and pion condensations in neutron star matter are investigated in this model. The existence of the pion condensations can postpone the appearance of delta isobars. We found that both the pion condensation and reduce of the ratio of delta isobar to nucleons couplings can soften the corresponding equation of state. The maximum masses and their corresponding radii of neutron stars are calculated, and the obtained values are in observational region.     

Neutron Star Motion in the Disk Galaxy

The neutron star motions are based on the undisturbed finitely thick galactic disk gravitational potential model. Two initial conditions, i.e. the locations and velocities, are considered. The Monte Carlo method is employed to separate rich diversities of the orbits of neutron stars into several sorts. The Poineare section has the potential to play an important role in the diagnosis of the neutron star motion. It has been observed that the increasing ratio of the motion range vertical to the galactic plane to that parallel to the galactic plane results in the irregularity of neutron star motion.     

Neutron Star Composition in Strong Magnetic Fields

We study the neutron star composition in the presence of a strong magnetic field. The effects of the anomalousmagnetic moments of both nucleons and electrons are investigated in relativistic mean field calculations for afl-equilibrium system. Since neutrons are fully spin polarized in a large field, generally speaking, the protonfraction can never exceed the field free case. An extremely strong magnetic field may lead to a pure neutronmatter instead of a proton-rich matter.     

Neutron Star Properties in a QCD-Motivated Model

We investigate the composition and structure of neutron-, hybrid-, and quark stars within an effective QCD-motivated model of strong interaction. The hadronic phase is described within a novel chiral SU(3) model and the deconfined quark-gluon plasma phase is formulated within the bag model. The phase transition between these phases is treated as a first order transition having two conserved charges.     

星模拟器星点能量中心修正方法的研究

对星模光学系统中各种像差对几何中心位置的影响及像差对显示星点能量中心位置造成的偏差进行了分析与综合评估.分析结果表明,视场位置越大的星点产生的像点能量越不均匀,重心偏移越明显,系统中慧差和畸变对于星点能量中心影响较大.根据球面镜组成的共轴光学系统性质可知,能量中心的偏移发生在星点所在极半径方向上,因此提出了一种基于极坐标的星点位置修正方法,只需在星点所在方向对极半径进行修正.该方法简化了基于二维坐标轴分区修正的过程,减少了数据计算量.利用极坐标修正方法对星模拟器修正前后的单星位置误差进行了测试,实验结果表明极坐标修正过程较以往修正方法简单快捷,且修正结果更加准确.     

Do Neutron Star Gravitational Waves Carry Superfluid Imprints?

Isolated neutron stars undergoing non-radial oscillations are expected to emit gravitational waves in the kilohertz frequency range. To date, radio astronomers have located about 1,300 pulsars, and can estimate that there are about 2×10⁸ neutron stars in the galaxy. Many of these are surely old and cold enough that their interiors will contain matter in the superfluid or superconducting state. In fact, the so-called glitch phenomenon in pulsars (a sudden spin-up of the pulsar's crust) is best described by assuming the presence of superfluid neutrons and superconducting protons in the inner crusts and cores of the pulsars. Recently there has been much progress on modelling the dynamics of superfluid neutron stars in both the Newtonian and general relativistic regimes. We will discuss some of the main results of this recent work, perhaps the most important being that superfluidity should affect the gravitational waves from neutron stars (emitted, for instance, during a glitch) by modifying both the rotational properties of the background star and the modes of oscillation of the perturbed configuration. Finally, we present an analysis of the so-called zero-frequency subspace (i.e., the space of time-independent perturbations) and determine that it is spanned by two sets of polar (or spheroidal) and two sets of axial (or toroidal) degenerate perturbations for the general relativistic system. As in the Newtonian case, the polar perturbations are the g-modes which are missing from the pulsation spectrum of a non-rotating configuration, and the axial perturbations should lead to two sets of r-modes when the degeneracy of the frequencies is broken by having the background rotate.     

208ΛPb的超子分布半径和中子星结构

从相对论平均场理论出发,考虑核子、超子和介子自由度,研究了208ΛPb的超子分布半径与中子星的性质以及它们之间的关系. 计算发现当超子的耦合常数比值由0.3增大到1时,对NLSH和NL3参数组,超核的超子分布半径分别由3.905和3.849fm增大到4.346和4.230fm,而中子星的最大质量分别由1.516和1.429M⊙增大到2.776和2.744M⊙,质量为1.4M⊙的中子星半径分别由13.13和12.79km增大到13.24和13.29km.即中子星的最大质量和半径随超子分布半径增大而增加. 这样只要从实验上确定208ΛPb的超子分布半径,就可以得到中子星结构的信息.