标题： 中子星的冷却与介子凝聚：低对称性能量模型中的可能快速冷却 显示英文标题

标题： Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a Low-Symmetry-Energy Model

摘要： 我们研究了包含介子凝聚核心的孤立中子星（NSs）的热演化，重点在于状态方程（EOS）的刚度。 许多温度观测结果可以通过排除快速中微子冷却过程的最小冷却情景来解释。 然而，几颗NSs足够冷，需要这种快速冷却过程。 NS冷却理论中最关键的问题是核子直接Urca（DU）过程是否开放。 如果核子对称能显著偏低，DU过程将被禁止。 因此，在这种EOS中需要另一种快速冷却过程。 作为解决这一问题的候选方案，我们考虑了介子凝聚。 我们表明，低对称能模型可以解释大多数冷却观测结果，包括冷NSs，同时具有强中子超流性。 同时，即使存在介子凝聚核心，它也能保持$2~M_{\odot}$观测结果。 因此，我们提出了介子凝聚的可能性，作为一种奇特状态来解决低对称能EOS中的问题。 我们还检查了我们的EOS与其他各种观测结果的一致性。 显示英文摘要

摘要： We studied thermal evolution of isolated neutron stars (NSs) including the pion condensation core, with an emphasis on the stiffness of equation of state (EOS). Many temperature observations can be explained by the minimal cooling scenario which excludes the fast neutrino cooling process. However, several NSs are cold enough to require it. The most crucial problem for NS cooling theory is whether the nucleon direct Urca (DU) process is open. The DU process is forbidden if the nucleon symmetry energy is significantly low. Hence, another fast cooling process is required in such an EOS. As the candidate to solve this problem, we consider the pion condensation. We show that the low-symmetry-energy model can account for most cooling observations including cold NSs, with strong neutron superfluidity. Simultaneously, it holds the $2~M_{\odot}$ observations even if the pion condensation core exists. Thus, we propose the possibility of pion condensation, as an exotic state to solve the problem in low-symmetry-energy EOSs. We examined the consistency of our EOSs with other various observations as well.