In neutron stars the nuclear asymmetric matter is expected to undergo phase transitions to a superfluid state. According to simple estimates, neutron matter in the inner crust and just below should be in the s-wave superfluid phase, corresponding to the neutron-neutron ${}^1{S}_0$ channel. At higher density in the core also the proton component should be superfluid, while in the inner core the neutron matter can be in the ${}^3{P}_2$ superfluid phase. Superluidity is believed to be at the basis of the glitches phenomenon and to play a decisive influence on many processes like transport, neutrino emission and cooling, and so on. One of the peculiarity of the superfluid phase is the presence of characteristic collective excitation, the so called ’phonons’, that correspond to smooth modulations of the order parameter and display a linear spectrum at low enough momentum. This paper is a brief review of the different phonons that can appear in Neutron Star superfuid matter and their role in several dynamical processes. Particular emphasis is put on the spectral functions of the different components, that is neutron, protons and electrons, which reveal their mutual influence. The open problems are discussed and indications on the work that remain to be done are given.

中文翻译：

---

中子星核中的超流体声子

在中子星中，核不对称物质有望发生相变，形成超流体状态。根据简单的估算，内壳中和正下方的中子物质应处于s波超流体相，对应于中子-中子${}^{\mathrm{1个}}{\mathrm{小号}}_0$渠道。在堆芯中较高的密度下，质子组分也应为超流体，而在堆芯中，中子物质可以在质子中。${}^3{P}_2$超流体相。人们认为超流体是毛刺现象的基础，并且对许多过程如运输，中微子排放和冷却等起决定性作用。超流体相的独特性之一是特征性集体激发的存在，即所谓的“声子”，其对应于阶数参数的平滑调制，并在足够低的动量下显示线性光谱。本文简要回顾了中子星超流体中可能出现的不同声子，以及它们在几个动力学过程中的作用。特别强调不同成分的光谱功能，即中子，质子和电子，它们揭示了它们的相互影响。讨论了未解决的问题，并给出了尚待完成的工作指示。