用于Nd I-V的激发与复合数据及其在千新星中的应用
Excitation and Recombination Data for Nd I-V with Applications to Kilonovae
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中文总结 AI 辅助
研究钕前五次电离阶段的原子数据，采用{\textsc autostructure}计算相关参数，对比不同方法结果，明确共振介导激发等的作用，为千新星观测及重元素形成研究提供原子基础。
中文摘要 AI 辅助
钕（Nd）是关键的r过程元素，会显著影响中子星并合产生的千新星的不透明度与出射光谱。我们给出了钕前五次电离阶段的新原子数据，重点关注与非局部热动平衡（non-LTE）建模相关的复合速率系数及电子碰撞激发。利用相对论原子结构程序{\textsc autostructure}，我们采用孤立共振近似计算了这些离子的能级、辐射复合与双电子复合速率，以及激发数据。激发数据集通过直接（扭曲波）和共振激发两种方法构建，可系统评估共振贡献对有效碰撞强度的影响。对于Nd {\textsc ii}，我们将碰撞强度与狄拉克原子R矩阵程序（{\textsc darc}）的结果进行对比，这些对比表明共振介导激发具有重要意义，尤其是对于低电荷离子，其近阈共振会显著提升速率。在高电离阶段的复合方面，双电子复合（DR）在宽温度范围内占主导，而对于近中性物种，辐射复合（RR）在低温下与DR相当。我们的结果凸显了非LTE原子物理在解释千新星观测结果、限定核合成产额方面的关键作用，本研究为将观测到的电磁信号与致密天体并合及重元素形成的物理过程关联起来所需的原子基础提供了支撑。
英文摘要
Neodymium (Nd), a key r-process element, significantly influences the opacity and emergent spectra of kilonovae resulting from neutron star mergers. We present new atomic data for the first five ionization stages of Neodymium, with emphasis on recombination rate coefficients and electron-impact excitation relevant to non-local thermodynamic equilibrium (non-LTE) modelling. Using the relativistic atomic structure code {\sc autostructure}, we compute energy levels, radiative and dielectronic recombination rates using the isolated-resonance approximation, and excitation data for these ions. Excitation datasets are constructed using both direct (distorted-wave) and resonant excitation approaches, allowing a systematic assessment of the impact of resonance contributions on effective collision strengths. For the case of Nd {\sc ii}, we compare collisional strengths with those produced by the Dirac Atomic R-matrix Codes ({\sc darc}). These comparisons demonstrate the importance of resonance-mediated excitation, especially for low-charge ions where near-threshold resonances significantly enhance rates. In terms of recombination for higher ionization stages, dielectronic recombination (DR) is found to dominate over a wide temperature range, while radiative recombination (RR) is comparable with DR at low temperatures for near-neutral species. Our results highlight the pivotal role of non-LTE atomic physics in interpreting kilonovae observations and constraining nucleosynthesis yields. This work strengthens the atomic foundation necessary for linking observed electromagnetic signals to the physics of compact object mergers and heavy element formation.
