The r-Process in Neutrino-driven Winds from Nascent, “Compact” Neutron Stars of Core-Collapse Supernovae
The r-Process in Neutrino-driven Winds from Nascent, “Compact” Neutron Stars of Core-Collapse Supernovae
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DOI：
10.1086/321339
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发表时间：
2001-02
期刊：
影响因子：
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通讯作者：
S. Wanajo;T. Kajino;G. Mathews;K. Otsuki
中科院分区：
文献类型：
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作者：
S. Wanajo;T. Kajino;G. Mathews;K. Otsuki
我们提出了核心坍缩超新星的新生中子星的中微子驱动的风的r-过程核合成的计算。对于富α冻结和随后的r过程，采用全动力学反应网络。中微子加热的喷出物的物理性质推导出一个广义相对论模型，其中假设球对称和稳定的流动。我们的研究结果表明，原中子星与一个大的压缩比提供了最强大的物理条件的r-过程。在这些“致密”原中子星的风中，即使是在熵为~ 100 NAk-200 NAk，中微子光度高达~1052 ergs-1的情况下，r-过程的第三个峰也能很好地再现。这是由于风中物质的动力学时间尺度很短。结果，A β 120的核的过量产生减少了（尽管A β 90的核的某些过量产生仍然是明显的）。每个事件的r-过程元素的丰度显着高于以往的研究。总积分核合成产额与太阳r-过程丰度模式符合得很好。我们的结果证实，中微子驱动的风情景仍然是形成太阳r过程丰度的一个有希望的地点。然而，我们最好的结果似乎意味着一个相当软的中子-星星状态方程和一个大质量的原中子星星，这是很难实现与标准的核心坍缩模型。我们提出，最有利的条件可能需要一个大质量的超新星祖先形成一个大质量的原中子星星吸积失败后，最初的中微子爆发。
We present calculations of r-process nucleosynthesis in neutrino-driven winds from the nascent neutron stars of core-collapse supernovae. A full dynamical reaction network for both the α-rich freezeout and the subsequent r-process is employed. The physical properties of the neutrino-heated ejecta are deduced from a general relativistic model in which spherical symmetry and steady flow are assumed. Our results suggest that proto-neutron stars with a large compaction ratio provide the most robust physical conditions for the r-process. The third peak of the r-process is well reproduced in the winds from these "compact" proto-neutron stars even for a moderate entropy, ~ 100NAk-200NAk, and a neutrino luminosity as high as ~1052 ergs s-1. This is due to the short dynamical timescale of material in the wind. As a result, the overproduction of nuclei with A ≲ 120 is diminished (although some overproduction of nuclei with A ≈ 90 is still evident). The abundances of the r-process elements per event is significantly higher than in previous studies. The total integrated nucleosynthesis yields are in good agreement with the solar r-process abundance pattern. Our results have confirmed that the neutrino-driven wind scenario is still a promising site in which to form the solar r-process abundances. However, our best results seem to imply both a rather soft neutron-star equation of state and a massive proto-neutron star that is difficult to achieve with standard core-collapse models. We propose that the most favorable conditions perhaps require that a massive supernova progenitor forms a massive proto-neutron star by accretion after a failed initial neutrino burst.