Transport Processes in Matter at High Temperatures and Densities

在恒星演化的后期，恒星内部的物质处于高温和高密度状态。在这样的条件下，在地球上的实验室里无法观察到的各种现象都可以很容易地实现。在本研究中，研究了中子星物质内部的以下基本过程。首先，即使是在地球实验室中很难产生的弱相互作用粒子（即构成宇宙暗物质的粒子），也可以在高温和高密度的条件下大量产生。计算了中子星物质中轴子的热产率。与x射线卫星对中子星表面温度的观测结果进行比较，将限制轴子的性质，轴子仍然是暗物质的最强候选者之一。虽然中微子也是弱相互作用粒子，但当温度和密度较高时，它们可能会被恒星物质散射而被困在恒星内部。更多的中微子“不透明度”被计算出来，它表达了在超新星爆炸中子星形成过程中散射发生的程度。该结果可用于确定是否出现介子凝聚相以及中子星是否保持引力稳定。通过对中子星表面温度的观测，可以发现中子星内部可能存在介子凝聚相。目前，利用人造卫星、航天飞机、空间站等在超高真空和微重力环境下进行科学实验和合成新材料。另一方面，在早期宇宙、超新星爆炸和星际空间等环境中，物质存在于各种条件下。综述了空间环境下与新材料合成有关的各种物理量，如重力加速度、温度、压力、质量密度、电场和磁场强度、能量、费米温度、超流/超导转变温度等，并与地球实验室条件下的物理量进行了比较。少

In late stages of stellar evolution, the matter inside stars is at high-temperatures and densities. Under such conditions, various phenomena that cannot be observed in the laboratory on Earth could be easily realized. In the present research, the following elementary processes inside neutron-star matter are studied.First, even weakly-interacting particles, which are hard to produce in the laboratory on Earth (i.e., such particles constitute the dark matter in the universe), could be copiously produced under high-temperature and high-density conditions. The rate of thermal production of axions in neutron-star matter is calculated. Acomparison with surface temperature observations of neutron stars with X-ray satellites will constrain the properties of the axion, which remains one of the strongest candidates for dark matter.While neutrinos are also weakly-interacting particles, they may be trapped inside stars due to scattering by stellar matter when temperature and density are high. The … More neutrino "opacity" is calculated, which expresses the degree to which scattering occurs during the formation of a neutron star in a supernova explosion. The result may be used to determine whether a kaon-condensed phase appears and whether the neutron star remains gravitationally stable. A possible existence of kaon-condensed phase inside neutron stars could be detected by observing the surface temperature of neutron stars.At present, artificial satellites, the space shuttle, the space station, etc., are used to conduct scientific experiments and to synthesize new materials under ultra-high vacuum and microgravity environments. On the other hand, matter exists under various conditions in such environments as the early universe, supernova explosion and interstellar space. Various physical quantities, such as gravitational acceleration, temperature, pressure, mass density, electric and magnetic field strengths, energy, Fermi temperature, superfluidity/superconductivity transition temperature, are reviewed under space environments and they are compared with those under the conditions in the laboratory on Earth in connection with the syntheses of new materials. Less