SolRaT：多项和多能级原子的极化谱线建模

中文摘要 AI 辅助

极化谱线的解释需要将统计平衡与极化辐射转移相结合的模型，该模型需考虑原子极化、Hanle效应以及Zeeman和Paschen-Back分裂。目标是提供Landi Degl`Innocenti和Landolfi（2004）（以下简称LL04）的不可约球张量形式主义的开源Python实现，用于Stokes轮廓的正演合成，并支持可互换的原子描述。SolRaT求解可互换的多项和多能级原子描述的统计平衡和极化转移问题。多项模型保留了同一项内精细结构能级之间的相干性，并通过精确对角化处理磁哈密顿量，使得磁分裂可以从线性Zeeman区制跟踪到不完全和完全Paschen-Back区制。广泛使用的多能级模型则仅假设线性Zeeman区制，导致更简单且更成熟的形式主义。该实现已针对LL04的解析结果、局部热力学平衡（LTE）Zeeman转移的Unno-Rachkovsky解、Hazel2的He I D3合成以及已发表的自治非LTE散射基准进行了验证。示例展示了项内磁混合如何产生与线性Zeeman多能级描述的偏差，以及如何使用J约束的多项方法在选定的精细结构分量上隔离这种效应。在相同条件下，使用可互换的多项和多能级描述合成相同的谱线，可以隔离项内磁混合和J间相干性相对于线性Zeeman响应的特征。这种受控比较对于开发适用于多种原子描述的散射极化诊断至关重要。

英文摘要

The interpretation of polarized spectral lines requires models that combine statistical equilibrium with polarized radiative transfer accounting for atomic polarization, the Hanle effect, and Zeeman and Paschen-Back splitting. The aim is to provide an open-source Python implementation of the irreducible spherical tensor formalism of Landi Degl`Innocenti and Landolfi (2004), hereafter LL04, for forward synthesis of Stokes profiles with interchangeable atomic descriptions. SolRaT solves the statistical equilibrium and polarized transfer problem for interchangeable multi-term and multi-level atomic descriptions. The multi-term model retains coherences between fine-structure levels of the same term and treats the magnetic Hamiltonian by exact diagonalization, allowing the magnetic splitting to be followed from the linear Zeeman regime to the incomplete and complete Paschen-Back regimes. The widely used multi-level model in turn assumes only the linear Zeeman regime, resulting in a simpler and more developed formalism. The implementation is checked against analytic results from LL04, the Unno-Rachkovsky solution for local thermodynamic equilibrium (LTE) Zeeman transfer, the Hazel2 He I D3 synthesis, and published self-consistent non-LTE scattering benchmarks. The examples show how the intra-term magnetic mixing produces departures from a linear Zeeman multi-level description, and how a J-constrained multi-term approach can be used to isolate this effect on a chosen fine-structure component. Synthesizing the same spectral line with interchangeable multi-term and multi-level descriptions under identical conditions isolates the signatures of intra-term magnetic mixing and inter-J coherences from the linear Zeeman response. Such controlled comparisons are central to developing scattering polarization diagnostics applicable across multiple atomic descriptions.

发表机构

• Institute of Physics of the National Academy of Sciences of Ukraine（乌克兰国家科学院物理研究所）
• Astronomical Observatory of the Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学天文台）

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