On the astrophysical robustness of the neutron star merger r-process
On the astrophysical robustness of the neutron star merger r-process
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DOI：
10.1111/j.1365-2966.2012.21859.x
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发表时间：
2012-11-01
影响因子：
4.8
通讯作者：
Winteler, C.
中科院分区：
文献类型：
--
作者：
Korobkin, O.;Rosswog, S.;Winteler, C.
在这项研究中，我们探索了紧凑二元合并动态喷射物中的核合成。我们特别感兴趣的问题是由此产生的丰度模式对合并系统的参数有多敏感。因此，我们系统地研究了1.0到2.0 M范围内的中子星质量组合？为了完整起见，我们将结果与中子星黑洞合并的两次模拟结果进行比较。对于所研究的系统，喷射物质量变化为 5 倍，但所有数量（在合并率的不确定性范围内）都与宇宙 r 过程的主要来源相一致。喷射物经历了强大的r过程核合成，以接近太阳的比率产生从第二到第三峰的所有元素。最引人注目的是，这个 r 过程非常稳健，所有 23 个研究的二元系统都产生几乎相同的丰度模式。这主要是由于喷射物中子含量极其丰富（Ye 类似于 0.04）以及 r 过程路径沿着中子滴线蜿蜒，因此丰度完全由核属性而不是天体物理属性决定。虽然与星系化学演化相关的进一步问题需要在未来的研究中探索，但我们认为这种鲁棒性以及第二个和第三个峰值重现的容易性，强烈表明紧凑的二元合并是观察到的独特重r过程成分来源的主要候选者。
In this study we explore nucleosynthesis in the dynamic ejecta of compact binary mergers. We are particularly interested in the question how sensitive the resulting abundance patterns are to the parameters of the merging system. Therefore, we systematically investigate combinations of neutron star masses in the range from 1.0 to 2.0 M? and, for completeness, we compare the results with those from two simulations of a neutron star black hole merger. The ejecta masses vary by a factor of 5 for the studied systems, but all amounts are (within the uncertainties of the merger rates) compatible with being a major source of the cosmic r-process. The ejecta undergo robust r-process nucleosynthesis which produces all the elements from the second to the third peak in close-to-solar ratios. Most strikingly, this r-process is extremely robust, and all 23 investigated binary systems yield practically identical abundance patterns. This is mainly the result of the ejecta being extremely neutron rich (Ye similar to 0.04) and the r-process path meandering along the neutron drip line so that the abundances are determined entirely by nuclear rather than astrophysical properties. While further questions related to galactic chemical evolution need to be explored in future studies, we consider this robustness together with the ease with which both the second and third peak are reproduced as strong indications that compact binary mergers are prime candidates for the sources of the observed unique heavy r-process component.