Khodel V A, Clark J W, Takano M, Zverev M V
Russian Research Centre Kurchatov Institute, Moscow 123182, Russia.
Phys Rev Lett. 2004 Oct 8;93(15):151101. doi: 10.1103/PhysRevLett.93.151101. Epub 2004 Oct 5.
A new scenario for neutron-star cooling is suggested by the correspondence between pion condensation, induced by critical spin-isospin fluctuations, and the metal-insulator phase transition in a 2D electron gas. Above the threshold density for pion condensation, the neutron single-particle spectrum acquires an insulating gap that quenches neutron contributions to neutrino production. In the liquid phase just below the transition, the fluctuations play dual roles by (i) creating a multisheeted neutron Fermi surface that extends to low momenta and activates the normally forbidden direct Urca cooling mechanism, and (ii) amplifying the nodeless P-wave neutron superfluid gap while suppressing S-wave pairing. Lighter stars without a pion-condensed core undergo slow cooling, whereas enhanced cooling occurs in heavier stars via direct Urca emission from a thin shell of the interior.
由临界自旋-同位旋涨落诱导的π介子凝聚与二维电子气中的金属-绝缘体相变之间的对应关系，为中子星冷却提出了一种新情况。高于π介子凝聚的阈值密度时，中子单粒子谱获得一个绝缘能隙，该能隙抑制了中子对中微子产生的贡献。在刚好低于转变温度的液相中，涨落起到双重作用：（i）形成一个延伸到低动量的多层中子费米面，并激活通常被禁止的直接乌卡冷却机制；（ii）增强无节点的P波中子超流能隙，同时抑制S波配对。没有π介子凝聚核心的较轻恒星经历缓慢冷却，而较重恒星则通过内部薄壳层的直接乌卡发射实现增强冷却。
