Collapsar R-process Yields Can Reproduce [Eu/Fe] Abundance Scatter in Metal-poor Stars
Collapsar R-process Yields Can Reproduce [Eu/Fe] Abundance Scatter in Metal-poor Stars
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DOI：
10.3847/1538-4357/ac00b2
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
K. Brauer;A. Ji;M. Drout;A. Frebel
中科院分区：
文献类型：
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作者：
K. Brauer;A. Ji;M. Drout;A. Frebel
目前尚不清楚中子星合并是否可以解释观测到的贫金属恒星的r过程丰度。坍缩星，这里定义为旋转的大质量恒星，其坍缩导致黑洞周围的圆盘迅速增加，可以发射喷气式飞机，是一个有希望的替代方案。我们发现我们可以产生一个自一致的模型，在这个模型中，具有随机铕产率的坍缩群可以合成金属贫（[Fe/H] < - 2.5）恒星中的所有r过程物质。我们的模型再现了观测到的[Eu/Fe]丰度的散射和散射的演化。我们发现，如果坍缩是贫金属恒星的主要r过程位点，则r过程合成可能与产生长γ射线暴的超新星有关。我们的研究结果还考虑到，除了那些发射γ射线爆发的超新星之外，核心坍缩超新星也可能产生r-过程物质（例如，可能是Ic-BL型超新星的一个子集）。此外，我们确定了坍缩星射流特性（各向同性能量、发动机亮度或发动机时间），可以追踪r-过程产率，并验证了我们模型中每个坍缩星产生的r-过程产率（~ 0.07M⊙）与其他独立估计一致。未来，在分布散点上达到0.05的指数精度或可靠的选择函数将进一步限制我们对r-process生产的探索。我们的模型也适用于另一个具有幂律产率的快速r过程站点，并且需要进行工作来确定，例如，快速合并的中子星是否也可以解释丰度散射。
It is unclear if neutron star mergers can explain the observed r-process abundances of metal-poor stars. Collapsars, defined here as rotating massive stars whose collapse results in a rapidly accreting disk around a black hole that can launch jets, are a promising alternative. We find that we can produce a self-consistent model in which a population of collapsars with stochastic europium yields synthesizes all of the r-process material in metal-poor ([Fe/H] < − 2.5) stars. Our model reproduces the observed scatter and evolution of scatter of [Eu/Fe] abundances. We find that if collapsars are the dominant r-process site for metal-poor stars, r-process synthesis may be linked to supernovae that produce long γ-ray bursts. Our results also allow for the possibility that core-collapse supernovae beyond those that launch γ-ray bursts also produce r-process material (e.g., potentially a subset of Type Ic-BL supernovae). Furthermore, we identify collapsar jet properties (isotropic energy, engine luminosity, or engine time) that may trace r-process yield and verify that the amount of r-process yield produced per collapsar in our model ( ∼ 0.07M ⊙) is consistent with other independent estimates. In the future, achieving 0.05 dex precision on distribution scatter or a reliable selection function would further constrain our probe of r-process production. Our model would also hold for another prompt r-process site with a power-law yield, and work is needed to determine if, for example, fast-merging neutron stars can also explain abundance scatter.