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arXiv 1203.4286nucl-thastro-ph.SR
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核相互作用对称性参数的约束

Constraining the Symmetry Parameters of the Nuclear Interaction

James M. Lattimer, Yeunhwan Lim

摘要:

稠密物质状态方程的主要不确定性之一是核对称能。对称能的密度依赖性在核天体物理学中很重要,因为它控制着核心坍缩超新星中物质的中子化、中子星的半径和壳的厚度、中子星的冷却速率以及r-过程核合成中所涉及的核的性质。我们发现,适合的核质量的实验质量,结合其他实验信息,从中子皮,重离子碰撞,巨偶极共振和偶极极化率,导致严格的约束参数,描述附近的核饱和密度的对称能。这些限制与纯中子物质理论计算的推论非常一致,而且与中子星的天体物理观测也非常一致。实验、理论和观测分析的一致性表明,对称性参数S_v和L分别在29.0 - 32.7 MeV和40.5 - 61.9 MeV范围内,对于一颗1.4 M太阳星,中子星半径在10.7 km < R < 13.1 km的窄窗口内(90%置信度)。我们还可以严格限制中子星壳的大小和它们所包含的部分转动惯量,以及1.4 M太阳星的总转动惯量和四极极化率。我们的研究结果也对包含中子星的致密并合的盘质量和喷射质量有影响。

英文摘要:

One of the major uncertainties in the dense matter equation of state has been the nuclear symmetry energy. The density dependence of the symmetry energy is important in nuclear astrophysics, as it controls the neutronization of matter in core-collapse supernovae, the radii of neutron stars and the thicknesses of their crusts, the rate of cooling of neutron stars, and the properties of nuclei involved in r-process nucleosynthesis. We show that fits of nuclear masses to experimental masses, combined with other experimental information from neutron skins, heavy ion collisions, giant dipole resonances and dipole polarizabilities, lead to stringent constraints on parameters that describe the symmetry energy near the nuclear saturation density. These constraints are remarkably consistent with inferences from theoretical calculations of pure neutron matter, and, furthermore, with astrophysical observations of neutron stars. The concordance of experimental, theoretical and observational analyses suggests that the symmetry parameters S_v and L are in the range 29.0 - 32.7 MeV and 40.5 - 61.9 MeV, respectively, and that the neutron star radius, for a 1.4 M_sun star, is in the narrow window 10.7 km < R < 13.1 km (90% confidence). We can also set tight limits to the size of neutron star crusts and the fractional moment of inertia they contain, as well as the overall moment of inertia and quadrupole polarizability of 1.4 M_sun stars. Our results also have implications for the disk mass and ejected mass of compact mergers involving neutron stars.

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