星系的能量平衡问题得以解决
The galaxies' energy balance problem solved
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中文总结 AI 辅助
本研究通过将星际介质的团块状结构纳入辐射转移模型，构建伪尘埃颗粒的亚网格方法，首次使侧视星系NGC 891实现良好能量平衡，且7个不同倾角星系的尘埃不透明度降低，B波段最大面光学深度下降1.3至2.8倍。
中文摘要 AI 辅助
我们尝试解决辐射转移（RT）模型长期存在的能量平衡问题，尤其针对侧视星系，方法是纳入对星际介质（ISM）团块状结构的处理。采用亚网格方法，将宁静尘埃云视为伪尘埃颗粒，赋予其等效的光学和热发射特性。推导吸收、散射和消光截面等关键量，可将宏观团块虚拟化为微观伪颗粒，使其能纳入现有尘埃模型组分。加入伪颗粒后，消光曲线更平缓。针对不同颜色和强度的辐射场，构建了团块发射光谱能量分布（SED）库。将新的团块状模型应用于侧视星系NGC 891，首次实现了良好的能量平衡，同时拟合了亚毫米（submm）和近红外（NIR）数据。该团块状模型还应用于7个不同倾角的小样本星系，并将结果与纯弥散模型的结果对比。与纯弥散对应模型相比，团块状模型的尘埃不透明度（因此消光）降低，因此从团块状模型推导得到的B波段最大面光学深度max(τ_B^f)降低了1.3至2.8倍。在这7个星系中，2个中心光学厚，2个中等光学厚，3个光学薄。
英文摘要
We attempt to resolve the long-standing energy balance problem encountered by Radiative Transfer (RT) models, particularly in edge-on galaxies by incorporating a treatment for the clumpy structure of the Interstellar Medium (ISM). A subgrid approach is adopted, treating the quiescent dust clouds as pseudo-dust grains, with equivalent optical and thermal emission properties. Deriving key quantities such as the absorption, scattering and extinction cross-sections enables the virtualisation of the macroscopic clump into a microscopic pseudo-grain that can be included alongside the existing dust model constituents. The addition of the pseudo-grain results in a flatter extinction curve. A library of clump emission spectral energy distributions (SEDs) is constructed for radiation fields of various colours and intensities. The new clumpy model is applied to the edge-on galaxy NGC 891 and, for the first time, is able to achieve a good energy balance, simultaneously fitting both the submm and Near Infrared (NIR) data. The clumpy model is further applied to a small sample of seven galaxies of various inclinations, and the results are compared with those from the purely diffuse models. The clumpy models are characterised by a reduction in dust opacity, and therefore attenuation, compared to their purely diffuse counterparts. Thus, the maximum face-on optical depth in the $B$-band, ${\mathrm max}(τ^{\mathrm f}_{\mathrm B})$, derived from the clumpy models is found to be lower by factors ranging from 1.3 to 2.8. Of the seven galaxies, two are found to be optically thick in their centres, two are found to be moderately optically thick, and three are found to be optically thin.
