Anderson-Bogoliubov phonons in the inner crust of neutron stars: Dipole excitation in a spherical Wigner-Seitz cell
Anderson-Bogoliubov phonons in the inner crust of neutron stars: Dipole excitation in a spherical Wigner-Seitz cell
复制标题
中子星内壳中的 Anderson-Bogoliubov 声子：球形维格纳-塞茨盒中的偶极子激发
DOI：
10.1103/physrevc.96.025806
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发表时间：
2017
影响因子：
3.1
通讯作者：
M. Matsuo
中科院分区：
文献类型：
--
作者：
T. Inakura;M. Matsuo
背景：Anderson-Bogoliubov(AB)声子，也被称为超流体声子，由于它可能影响中子星内壳的热导率和其他性质而引起人们的关注。然而，关于AB声子的微观研究还很少，其中明确考虑了团簇的存在。目的：为了获得与AB声子和晶格声子之间的耦合有关的微观信息，我们打算阐明团簇的存在对AB声子的影响。方法：采用Hartree-Fock-Bogoliubov模型和球形Wigner-Seitz盒中的准粒子随机相近似来描述中子超流及其相关的集体激发.我们通过改变单元中的中子化学势和质子数来对偶极激发进行系统的数值计算。结果：该模型预测了偶极AB声子模的系统出现，但在团簇内部却表现出对声子振幅的强烈抑制。我们还发现，团簇表面附近的声子振幅随中子密度的变化而变化。在较高的中子密度下，AB声子模表现出类似于丰中子核中的侏儒偶极共振的行为。这表明AB声子和晶格声子之间的耦合可能较弱。
Background: The Anderson-Bogoliubov (AB) phonon, called also the superfluid phonon, has attracted attentions since it may influence the thermal conductivity and other properties of inner crust of neutron stars. However, there are limited number of microscopic studies of the AB phonon where the presence of clusters is explicitly taken into account.\\ Purpose: We intend to clarify how the presence of clusters affects the AB phonon in order to obtain microscopic information relevant to the coupling between the AB phonon and the lattice phonon. \\ Methods: The Hartree-Fock-Bogoliubov model and the quasiparticle random-phase approximation formulated in a spherical Wigner-Seitz cell are adopted to describe neutron superfluidity and associated collective excitations. We perform systematic numerical calculations for dipole excitation by varying the neutron chemical potential and the number of protons in a cell. \\ Results:The model predicts systematic emergence of the dipole AB phonon mode, which however exhibits strong suppression of phonon amplitude inside the cluster. We find also that the phonon amplitude around the cluster surface varies as the neutron density. At higher neutron densities the AB phonon mode exhibits behaviour similar to the pygmy dipole resonance in neutron-rich nuclei.\\ Conclusions: The dipole AB phonon mode does not penetrate into the clusters. This suggests that the coupling between the AB phonon and the lattice phonon may be weak.