AI 中文总结
该研究针对星系中电离气体发射线相关问题，提出用于SKIRT的新光电离模块，结合Cloudy表等计算三维电离气体发射线光度，经与Cloudy、COLT验证，该模块能实现自洽合成观测，适用于流体动力学模拟。
AI 中文摘要
来自电离气体的发射线是星系中恒星形成、金属丰度和电离条件的关键诊断依据。解释积分场巡天（如MaNGA、MUSE、JWST/NIRSpec）的空间分辨观测结果并将其与流体动力学模拟进行比较，需要能处理实际几何形状、尘埃衰减和合成仪器输出的三维光电离模型。我们为蒙特卡罗辐射传输代码SKIRT提出了一个新的光电离模块，它结合预先计算的用于气体温度和不透明度的Cloudy表，直接计算离子分数和线发射率，来预测三维电离气体的发射线光度。局部电离辐射场（1 - 6里德）由log U和四个光谱形状比来表征；Cloudy表将这些映射到温度和不透明度，通过SKIRT现有的迭代循环收敛。然后一个内联求解器根据收敛的场和温度确定离子分数并评估线发射率。我们在60个球壳模型上与Cloudy进行验证，在一个类似银河系的星系上与COLT进行验证。在一维网格上，氢复合线与Cloudy的符合度在百分之几以内（Hα中位数比率0.97），禁线在约5%以内，除了[S II] 6717（1.23），其偏移量表明在电离前沿附近温度估计过高。在三维中，氢线的积分光度与COLT的符合度在18%以内，[N II]在2%以内，而[O III]和[S II]分别升高了约70%和80%。逐像素相关系数达到r >= 0.92，光度加权散射为0.14 - 0.31 dex，BPT比率大致一致。该模块能够在单次蒙特卡罗辐射传输运行中计算电离气体发射线、尘埃衰减和尘埃再发射，实现自洽合成观测，适用于任何流体动力学模拟。
英文摘要
Emission lines from ionised gas are key diagnostics of star formation, metallicity, and ionisation conditions in galaxies. Interpreting spatially resolved observations from integral-field surveys (e.g. MaNGA, MUSE, JWST/NIRSpec) and comparing them with hydrodynamical simulations requires 3D photoionisation models that handle realistic geometries, dust attenuation, and synthetic instrument output. We present a new photoionisation module for the Monte Carlo radiative transfer code SKIRT that predicts emission-line luminosities of ionised gas in 3D, combining pre-computed Cloudy tables for gas temperature and opacity with a direct calculation of ion fractions and line emissivities. The local ionising radiation field (1-6 Ryd) is characterised by log U and four spectral-shape ratios; Cloudy tables map these to temperature and opacity, converging through SKIRT's existing iteration cycle. An inline solver then determines ion fractions from the converged field and temperature and evaluates line emissivities. We validate against Cloudy on 60 spherical shell models and against COLT on a Milky Way-analogue galaxy. On the 1D grid, hydrogen recombination lines agree with Cloudy to within a few per cent (Halpha median ratio 0.97) and the forbidden lines to within ~5%, except [S II] 6717 (1.23), whose offset traces a temperature overestimate near the ionisation front. In 3D, integrated luminosities agree with COLT to within 18% for the hydrogen lines and 2% for [N II], while [O III] and [S II] are elevated by ~70 and ~80%. Pixel-by-pixel correlation coefficients reach r >= 0.92, with luminosity-weighted scatter of 0.14-0.31 dex and broadly consistent BPT ratios. The module enables self-consistent synthetic observations in which ionised-gas emission lines, dust attenuation, and dust re-emission are computed in a single MCRT run, applicable to any hydrodynamical simulation.
Comments18 pages, 17 figures, 10 tables. Submitted to A&A
