发表机构
Tsinghua University; Anqing Normal University; The University of Hong Kong（清华大学; 安庆师范大学; 香港大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用恒星种群模型探讨1.6 μm H⁻凸起作为TP-AGB贡献与近期熄灭的诊断，发现其增强依赖TP-AGB光及模板，结合光学特征可提供额外熄灭信息。
AI 中文摘要
1.6 μm H⁻ 凸起源于冷恒星大气中负氢离子不透明度的最小值。尽管它被认为是星系光谱中的常见特征，但其在研究恒星种群和近期熄灭方面的潜力仍鲜有探索。在中间年龄时，其增强在某些具有显著热脉冲渐近巨星分支（TP-AGB）贡献的恒星种群模型中表现强烈，而在其他模型中则微弱或缺失。这种变化使得该特征既可能成为年龄诊断工具，也可能成为模型不确定性的来源。我们使用基于 X-shooter 光谱库（XSL）和灵活恒星种群合成（FSPS）的模型来检验驱动这一行为的因素及其对熄灭的揭示作用。受控的 FSPS 实验表明，H⁻ 凸起取决于 TP-AGB 光的数量以及用于表示它的恒星模板。采用的 XSL 和启用 TP-AGB 的 FSPS 模型预测了快速熄灭后的瞬态增强，其年龄响应与光学光谱特征不同。因此，结合这些诊断可以提供关于近期熄灭的额外信息，尽管解释依赖于种群模型和恒星形成历史。与现有 JWST 光谱的示例性比较表明，包含 TP-AGB 贡献的模型能够较好地描述观测到的 H⁻ 区域。这些结果激励进一步利用 H⁻ 凸起来检验 TP-AGB 方案，并利用当前和即将到来的观测研究熄灭。
英文摘要
The 1.6 $μ\mathrm{m}$ $\rm{H^{-}}$ bump arises from a minimum in the opacity of the negative hydrogen ion in cool stellar atmospheres. Although it is recognized as a common feature in galaxy spectra, its potential for studying stellar populations and recent quenching remains little explored. Its enhancement at intermediate ages is strong in some stellar population models with substantial thermally pulsing asymptotic giant branch (TP-AGB) contributions but weak or absent in others. This variation makes the feature both a potential age diagnostic and a source of model uncertainty. We use models based on the X-shooter Spectral Library (XSL) and Flexible Stellar Population Synthesis (FSPS) to examine what drives this behavior and what it can reveal about quenching. Controlled FSPS experiments show that the $\rm{H^{-}}$ bump depends on both the amount of TP-AGB light and the stellar template used to represent it. The adopted XSL and TP-AGB-on FSPS models predict a transient enhancement following rapid quenching, with a different age response from optical spectral features. Combining these diagnostics can therefore provide additional information about recent quenching, although the interpretation depends on the population model and star-formation history. An illustrative comparison with existing JWST spectra shows that models including TP-AGB contributions can describe the observed $\rm{H^{-}}$ region reasonably well. These results motivate further use of the $\rm{H^{-}}$ bump to test TP-AGB prescriptions and investigate quenching with current and forthcoming observations.
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