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arXiv 1901.01747astro-ph.GA
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G.A.S. II:星系中的尘埃消光;光度函数和InfraRed eXcess

G.A.S. II: Dust extinction in galaxies; Luminosity functions and InfraRed eXcess

M. Cousin, V. Buat, G. Lagache, M. Bethermin

摘要:

尘埃是星系星际介质的重要组成部分。尘埃的存在强烈影响了星系内恒星产生的光。由于这些光子是我们探索恒星质量组合的主要信息载体,因此了解星系的演化,模拟星系的发光特性并考虑尘埃的影响是半解析模型的一个基本挑战。该模型基于源自气体结构的物理激励湍流模型(G.A.S. I paper).粉尘影响的处理考虑到三个粉尘成分:多环芳烃,非常小的颗粒,大颗粒。所有这三种成分都以扩散和碎片/致密气相的形式出现。每个阶段都有自己的恒星,尘埃含量和几何形状。尘埃含量的变化与其伴生相的金属丰度有关。模型用于预测从$z=9.0$到$z=0.1$的UV和IR光度函数。我们的两相ISM处方很好地捕捉了UV和IR光度函数的演变。我们注意到在低红移($z<0.5$)的红外光度的一个小的过度生产。我们还重点讨论了剩余辐射(IRX),并探讨了它与恒星质量,UV斜率,恒星年龄,金属丰度和衰减曲线的斜率的依赖关系。我们的模型预测大的散射关系的基础上IRX,特别是IRX- $β$关系。我们的分析表明,衰减曲线的斜率是更多地由绝对衰减在FUV波段比磁盘倾斜驱动。我们证实,恒星星族年龄和衰减曲线的斜率都可以移动星系低于基准恒星出生关系的IRX- $β$图。

英文摘要:

Dust is a crucial component of the interstellar medium of galaxies. The presence of dust strongly affects the light produced by stars within a galaxy. As these photons are our main information vector to explore the stellar mass assembly and therefore understand a galaxy's evolution, modeling the luminous properties of galaxies and taking into account the impact of the dust is a fundamental challenge for semi-analytical models.We present the complete prescription of dust attenuation implemented in the new semi-analytical model: G.A.S. This model is based on a two-phase medium originating from a physically motivated turbulent model of gas structuring (G.A.S. I paper). Dust impact is treated by taking into account three dust components: Polycyclic Aromatic Hydrocarbons, Very Small Grains, and Big Grains. All three components evolve in both a diffuse and a fragmented/dense gas phase. Each phase has its own stars, dust content and geometry. Dust content evolves according to the metallicity of it associated phase.The G.A.S. model is used to predict both the UV and the IR luminosity functions from $z=9.0$ to $z=0.1$. Our two-phase ISM prescription catches very well the evolution of UV and IR luminosity functions. We note a small overproduction of the IR luminosity at low redshift ($z<0.5$). We also focus on the Infrared-Excess (IRX) and explore its dependency with the stellar mass, UV slope, stellar age, metallicity and slope of the attenuation curves. Our model predicts large scatters for relations based on IRX, especially for the IRX-$β$ relation. Our analysis reveals that the slope of the attenuation curve is more driven by absolute attenuation in the FUV band than by disk inclination. We confirm that the age of the stellar population and the slope of the attenuation curve can both shift galaxies below the fiducial star-birth relation in the IRX-$β$ diagram.

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