Neutron star (NS) merger ejecta offer viable sites for the production of heavy $r$-process elements with nuclear mass numbers $A\gtrsim 140$. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties. Here, we introduce improvements to our scission-point model, called SPY, to derive the fission fragment distribution for all neutron-rich fissioning nuclei of relevance in $r$-process calculations. These improvements include a phenomenological modification of the scission distance and a smoothing procedure of the distribution. Such corrections lead to much better agreement with experimental fission yields. Those yields are also used to estimate the number of neutrons emitted by the excited fragments on the basis of different neutron evaporation models. Our fission yields are extensively compared to those predicted by the GEF (general description of fission observables) model. The impact of fission on the $r$-process nucleosynthesis in binary neutron mergers is also reanalyzed. Two scenarios are considered, the first one with low initial electron fraction subject to intense fission recycling, in contrast to the second one, which includes weak interactions on nucleons. The various regions of the nuclear chart responsible for fission recycling during the neutron irradiation and after freeze-out are discussed. The contribution fission processes may have to the final abundance distribution is also studied in detail in the light of newly defined quantitative indicators describing the fission recycling, the fission seeds, and the fission progenitors. In particular, those allow us to estimate the contribution of fission to the final abundance distribution stemming from specific heavy nuclei. Calculations obtained with SPY and GEF fission fragment distributions are compared for both $r$-process scenarios.

中文翻译：

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中子星合并中裂变碎片的分布及其对热过程核合成的影响

中子星（NS）合并喷射器为重装生产提供了可行的场所 $\mathrm{[R}$核质量数的过程元素 $\mathrm{一种}\gtrsim 140$。裂变循环的至关重要的作用是该站点抵抗许多天体物理不确定性的鲁棒性。在这里，我们对称为SPY的分裂点模型进行了改进，以得出与中子相关的所有富中子裂变核的裂变碎片分布。$\mathrm{[R}$-过程计算。这些改进包括切变距离的现象学修改和分布的平滑过程。这样的修正导致与实验裂变产率更好的一致性。这些产量还用于根据不同的中子蒸发模型估算受激发碎片发射的中子数量。我们的裂变产率已与GEF（裂变观测物的一般描述）模型预测的产率进行了广泛比较。裂变对$\mathrm{[R}$还对二元中子合并中的过程核合成进行了重新分析。考虑了两种情况，第一种情况的初始电子分数低，容易发生强烈的裂变循环，而第二种情况则包括在核子上的弱相互作用。讨论了在中子辐照期间和冻结后负责裂变再循环的核图的各个区域。根据新定义的描述裂变循环，裂变种子和裂变祖先的定量指标，也详细研究了裂变过程对最终丰度分布的贡献。特别是，这些使我们能够估计裂变对源自特定重核的最终丰度分布的贡献。$\mathrm{[R}$处理方案。