THE COOLING OF THE CASSIOPEIA A NEUTRON STAR AS A PROBE OF THE NUCLEAR SYMMETRY ENERGY AND NUCLEAR PASTA
THE COOLING OF THE CASSIOPEIA A NEUTRON STAR AS A PROBE OF THE NUCLEAR SYMMETRY ENERGY AND NUCLEAR PASTA
复制标题
DOI：
10.1088/2041-8205/779/1/l4
复制
发表时间：
2013-08
期刊：
影响因子：
--
通讯作者：
W. Newton;K. Murphy;J. Hooker;Bao-An Li
中科院分区：
文献类型：
--
作者：
W. Newton;K. Murphy;J. Hooker;Bao-An Li
在过去的十年中，对Cas A超新星遗迹中的中子星星（NS）的X射线观测表明，这颗星星的表面温度正在迅速下降20%-5.5%。一种解释认为，快速冷却是由星星核心的中子超流性引发的，导致中子库珀对断裂和形成（PBF）的中微子发射增强。使用一致的NS地壳和核心的状态方程（EOS）和成分，我们探索这种解释的灵敏度的对称性能量L的EOS的密度依赖性，并存在增强中微子冷却的气泡阶段的地壳“核面食”。在NS群众和信封组成的保守范围内的冷却建模，我们发现L 70兆电子伏，与地面实验的限制和其他天体物理观测的竞争力。对于接近最可能质量M <$1.65 M的质量，约束变得更加严格35 <$L <$55 MeV。气泡冷却过程的加入降低了星星在PBF阶段的冷却速率，只有当L <$45 MeV时才能与观测到的速率相匹配，考虑到所有质量，对应于NS半径<$11 km。
X-ray observations of the neutron star (NS) in the Cas A supernova remnant over the past decade suggest the star is undergoing a rapid drop in surface temperature of ≈2%–5.5%. One explanation suggests the rapid cooling is triggered by the onset of neutron superfluidity in the core of the star, causing enhanced neutrino emission from neutron Cooper pair breaking and formation (PBF). Using consistent NS crust and core equations of state (EOSs) and compositions, we explore the sensitivity of this interpretation to the density dependence of the symmetry energy L of the EOS used, and to the presence of enhanced neutrino cooling in the bubble phases of crustal “nuclear pasta.” Modeling cooling over a conservative range of NS masses and envelope compositions, we find L ≲ 70 MeV, competitive with terrestrial experimental constraints and other astrophysical observations. For masses near the most likely mass of M ≳ 1.65 M☉, the constraint becomes more restrictive 35 ≲ L ≲ 55 MeV. The inclusion of the bubble cooling processes decreases the cooling rate of the star during the PBF phase, matching the observed rate only when L ≲ 45 MeV, taking all masses into consideration, corresponding to NS radii ≲ 11 km.