中子星内重子直接URCA过程的研究

发布时间：2018-04-13 12:43

  本文选题：中子星 + 超子　； 参考：《吉林大学》2016年博士论文

【摘要】：中子星热演化的研究是当前核天体物理领域的前沿课题。本文主要是在相对论平均场理论与相对论Hartree-Fork框架下,在考虑SU(3)对称的超子—介子耦合、含有δ介子及矢量介子张量相互作用的情况下,在中子星内直接URCA过程方面取得了以下三方面的研究结果:首先,在相对论平均场框架下利用GM1和TM1模型参数,研究中子星内重子直接URCA过程的特点。一方面,我们采用SU(6)和SU(3)对称下的超子—介子耦合参数来研究核子和超子直接URCA过程的特点。计算结果表明由于超子的出现使质子和轻子的丰度变小,导致核子直接URCA的中微子发射率变小。另一方面,我们研究了SU(3)对称下超子自由度对总中微子发射率和中微子光度的影响。结果表明在大部分重子数密度区域,SU(3)对称性下核子直接URCA过程的中微子发射率大于在SU(6)对称性下的中微子发射率,超子直接URCA过程也有类似的趋势。另外,我们发现无论是否出现超子,重子直接URCA过程总中微子发光度都是先增加后减小,这表明同一个发光度会对应两颗质量不同的中子星。其次,在相对论平均场理论框架下,我们研究了超子星内同位旋矢量-标量δ介子引入对核子和超子直接URCA过程的影响。结果表明,δ介子出现使核子和超子有效质量发生劈裂,质子和Λ、Σ0、Σ-超子的丰度明显增加,并且导致核子和超子直接URCA过程中微子发射率明显增加,可以预期δ介子的引入将加快中子星的冷却速度。最后,在相对论Hartree-Fork近似方法下,研究ω和ρ介子张量相互作用对传统中子星(npeμ物质)内直接URCA过程的影响,并且结合Bardeen-Cooper-Schrieffer(BCS)理论研究了ω和ρ介子张量相互作用对核子超流的影响。结果表明,在核子数密度大于0.42fm-3的区域,包含ω和ρ介子张量耦合时的核子直接URCA过程中微子发射率明显大于不包含ω和ρ介子张量耦合时的核子直接URCA过程中微子发射率。此外,ω和ρ介子张量耦合对核子01对能隙的影响也很明显。结果表明包含ω和ρ介子张量耦合相互作用导致中子1S0对能隙明显增加,特别是中子01对能隙的峰值增长了约44%;质子01对能隙在ρ=0.0~0.079fm-3核子数密度区域减小,在ρ=0.079~0.383fm-3密度区域增加。这些变化必然会影响中子星的冷却性质。我们的结果为研究ω和ρ介子张量耦合相互作用对中子星冷却性质的影响提供了基础。
[Abstract]:The thermal evolution of neutron stars is a frontier subject in the field of nuclear astrophysics.In this paper, under the framework of relativistic mean field theory and relativistic Hartree-Fork, the symmetric hyperon-meson coupling with 未 meson and vector meson Zhang Liang is considered.The research results of direct URCA processes in neutron stars are as follows: firstly, the characteristics of direct URCA processes in neutron stars are studied by using the parameters of GM1 and TM1 models under the framework of relativistic mean field.On the one hand, we study the characteristics of direct URCA processes of nucleons and hyperons by using the hyperon-meson coupling parameters under the symmetry of Su ~ (6) and Su ~ (3).The results show that the abundance of protons and leptons is reduced due to the appearance of hyperons, which leads to the reduction of neutrino emissivity of nucleon direct URCA.On the other hand, we study the effect of hyperon degree of freedom on the total neutrino emissivity and neutrino luminosity under SUP3) symmetry.The results show that the neutrino emissivity of the nucleon direct URCA process is higher than that of the nucleon direct URCA process under most baryon density regions. The direct URCA process has a similar trend.In addition, we find that the total neutrino luminosity of baryon direct URCA process increases first and then decreases, which indicates that the same luminosity will correspond to two neutron stars with different mass.Secondly, in the framework of relativistic mean field theory, we study the influence of the introduction of isospin vector-scalar mesons on the direct URCA processes of nucleons and hyperons.The results show that the appearance of 未 mesons cleavage the effective mass of nucleon and hyperon, increase the abundance of proton and 鈭，

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