未探测到 HC(S)SH：估算上限并约束化学
Non-detection of HC(S)SH: Estimating Upper Limits and Constraining Chemistry
AI总结：
通过独立重新分析 ALMA 数据集，发现先前声称的 t-HC(S)SH 探测实为光谱混合所致，并给出了严格的柱密度上限（≤4×10^14 cm^-2）和丰度上限（≤1×10^-10），建立了未来搜寻含硫物种的严谨框架。
摘要：
在恒星形成区搜寻二硫代甲酸（t-HC(S)SH）对于理解星际硫化学和解决“缺失硫”问题至关重要。受最近声称在 NGC 1333 IRAS 4A2 中探测到 t-HC(S)SH 的启发，我们使用综合光谱和化学模型独立重新分析了相同的 ALMA 数据集。我们没有发现 t-HC(S)SH 的可信证据：所有报告的跃迁完全由已知的、丰富的分子解释，没有 t-HC(S)SH 独有的无混合特征。我们批判性地重新评估了报告的探测，推导出严格的柱密度上限（N_t-HC(S)SH ≤ 4×10^14 cm^-2）和分数丰度上限（相对于 H2 ≤ 1×10^-10）。我们的天体化学模型将这些上限置于背景中，表明声称的探测可能源于光谱混合和不一致的建模假设。鉴于热核环境中复杂且双硫取代分子的稀有性，未探测与化学预期一致。此外，我们的分析建立了一个严格的框架，以指导未来对含硫物种的搜寻，并强调了在天体化学中进行彻底谱线识别和建模实践的关键重要性。
英文摘要：
The search for dithioformic acid (t-HC(S)SH) in star-forming regions is crucial for understanding interstellar sulfur chemistry and addressing the 'missing sulfur' problem. Motivated by a recent claim of t-HC(S)SH detection in NGC 1333 IRAS 4A2, we independently reanalyzed the same ALMA dataset using comprehensive spectral and chemical modeling. We find no credible evidence for t-HC(S)SH: all reported transitions are fully accounted for by known, abundant molecules, with no unblended features unique to t-HC(S)SH. We critically reassess the reported detection, deriving stringent upper limits on the column density (N_t-HC(S)SH <= 4 x 10^14 cm^-2) and the fractional abundance (<= 1 x 10^-10 relative to H2). Our astrochemical models place these limits in context, showing the claimed detection likely results from spectral blending and inconsistent modeling assumptions. The non-detection aligns with chemical expectations given the rarity of complex and doubly sulfur-substituted molecules in hot corino environments. Furthermore, our analysis establishes a rigorous framework to guide future searches for sulfur-bearing species and highlights the critical importance of thorough line identification and modeling practices in astrochemistry.
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