Radiative transfer meets Bayesian statistics: where does a galaxy's [C II] emission come from?
Radiative transfer meets Bayesian statistics: where does a galaxy's [C II] emission come from?
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DOI：
10.1093/mnras/stw2580
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发表时间：
2016-07
影响因子：
4.8
通讯作者：
Gioacchino Accurso;A. Saintonge;T. Bisbas;S. Viti
中科院分区：
文献类型：
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作者：
Gioacchino Accurso;A. Saintonge;T. Bisbas;S. Viti
[CII] 158 μm发射线可以出现在星际介质（ISM）的所有阶段，因此在进行星系范围的综合[C II]观测时，能够解开不同的贡献是一个重要但尚未解决的问题。我们提出了一个新的多相三维辐射传输接口，耦合STARBURST 99，恒星分光光度计代码，与光电离和天体化学代码MOCASSIN和3D-PDR。我们模拟整个恒星形成的地区，包括电离，原子和分子阶段的ISM，并应用贝叶斯推理方法来参数化的[C II]发射的分数来自分子区域，f[CII]，摩尔，作为一个函数的典型的综合性质的星系在本地宇宙的变化。影响f[C II]，mol变化的主要参数是比星星形成率（SSFR）、气相金属丰度、H II区电子数密度（ne）和尘埃质量分数。例如，当ne从101.5 cm−3增加到102.5 cm−3，或者SSFR从10−9.6 yr − 1减少到10−10.6 yr−1时，f[CII]，mol可以从60%增加到80%。我们的模型预测银河系的f[CII]，mol = 75.8 ± 5.9%，与测量值75%一致。当把新的公式应用于来自Herschel参考巡天的完整星系样本时，我们发现总的积分[CII]发射的60%到80%来自分子区域。
The [CII] 158 μm emission line can arise in all phases of the interstellar medium (ISM), therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated [C II] observations. We present a new multiphase 3D radiative transfer interface that couples STARBURST99, a stellar spectrophotometric code, with the photoionization and astrochemistry codes MOCASSIN and 3D-PDR. We model entire star-forming regions, including the ionized, atomic, and molecular phases of the ISM, and apply a Bayesian inference methodology to parametrize how the fraction of the [C II] emission originating from molecular regions, f[CII],mol, varies as a function of typical integrated properties of galaxies in the local Universe. The main parameters responsible for the variations of f[C II],mol are specific star formation rate (SSFR), gas phase metallicity, H II region electron number density (ne), and dust mass fraction. For example, f[CII],mol can increase from 60 to 80 per cent when either ne increases from 101.5 to 102.5 cm−3, or SSFR decreases from 10−9.6 to 10−10.6 yr−1. Our model predicts for the Milky Way that f[C II],mol = 75.8 ± 5.9 per cent, in agreement with the measured value of 75 per cent. When applying the new prescription to a complete sample of galaxies from the Herschel Reference Survey, we find that anywhere from 60 to 80 per cent of the total integrated [CII] emission arises from molecular regions.