Evolution of Proto-Neutron Stars with Kaon Condensates
Evolution of Proto-Neutron Stars with Kaon Condensates
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DOI：
10.1086/320642
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发表时间：
2000-08
期刊：
影响因子：
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通讯作者：
J. Pons;J. Miralles;M. Prakash;J. Lattimer
中科院分区：
文献类型：
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作者：
J. Pons;J. Miralles;M. Prakash;J. Lattimer
我们提出了一个原中子星星的演化，其中可能存在的K介子凝聚物质的模拟，包括有限的温度和被困中微子的影响。从纯核子物质到K介子凝聚相的相变用吉布斯相平衡规则描述，该规则允许混合相的存在。含有K介子凝聚的中子星的一个普遍性质，以及其他形式的奇异性，是冷的、无中微子的物质的最大质量可能小于含有被捕获的中微子或具有有限熵的物质的最大质量。因此，一颗原中子星星的重子质量超过了冷的无中微子物质的最大质量，因此是亚稳态的，也就是说，它会在开尔文-亥姆霍兹冷却阶段的某个时候坍缩成黑洞。K介子凝聚对亚稳恒星的影响是戏剧性的。在这些情况下，来自一颗假想的银河系超新星（距离~8.5 kpc）的中微子信号会突然停止，通常会在超级神冈和萨德伯里中微子天文台探测器的背景之上，这些探测器具有低能量阈值和背景。这与稳定星星的情况相反，稳定恒星的信号呈指数衰减，最终消失在背景中。我们发现K介子凝聚的亚稳恒星的寿命被限制在40-70秒的范围内，并弱依赖于原中子星星质量，形成鲜明对比的显着更大的质量依赖性和范围（1-100秒）的超子丰富的亚稳恒星。我们发现，一个独特的签名K介子凝聚将是难以识别的。K介子凝聚体的形成被推迟到开尔文-亥姆霍兹时期的最后阶段，那时中微子的光度相对较小。在稳定的恒星中，凝聚态的出现对中微子信号的调制太小，以至于无法用现有的探测器清楚地分辨出来，尽管核心存在一级相变。在亚稳恒星中，中微子信号的突然中断会发生，不管它是由K介子凝聚、超子还是夸克引起的。但是，如果亚稳星星的寿命小于30 s左右，我们发现它不太可能是由于K介子凝聚。
We present simulations of the evolution of a proto-neutron star in which kaon-condensed matter might exist, including the effects of finite temperature and trapped neutrinos. The phase transition from pure nucleonic matter to the kaon condensate phase is described using Gibbs' rules for phase equilibrium, which permit the existence of a mixed phase. A general property of neutron stars containing kaon condensates, as well as other forms of strangeness, is that the maximum mass for cold, neutrino-free matter can be less than the maximum mass for matter containing trapped neutrinos or that has a finite entropy. A proto-neutron star formed with a baryon mass exceeding that of the maximum mass of cold, neutrino-free matter is therefore metastable, that is, it will collapse to a black hole at some time during the Kelvin-Helmholtz cooling stage. The effects of kaon condensation on metastable stars are dramatic. In these cases, the neutrino signal from a hypothetical galactic supernova (distance ~8.5 kpc) will stop suddenly, generally at a level above the background in the Super-Kamiokande and Sudbury Neutrino Observatory detectors, which have low-energy thresholds and backgrounds. This is in contrast to the case of a stable star, for which the signal exponentially decays, eventually disappearing into the background. We find the lifetimes of kaon-condensed metastable stars to be restricted to the range of 40-70 s and weakly dependent on the proto-neutron star mass, in sharp contrast to the significantly larger mass dependence and range (1-100 s) of hyperon-rich metastable stars. We find that a unique signature for kaon condensation will be difficult to identify. The formation of the kaon condensate is delayed until the final stages of the Kelvin-Helmholtz epoch, when the neutrino luminosity is relatively small. In stable stars, modulations of the neutrino signal caused by the appearance of the condensate will therefore be too small to be clearly distinguished with current detectors, despite the presence of a first-order phase transition in the core. In metastable stars, the sudden cessation in the neutrino signal occurs whether it is caused by kaon condensation, hyperons, or quarks. However, if the lifetime of the metastable star is less than about 30 s, we find that it is not likely to be due to kaon condensation.