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从远紫外到远红外——z=0处L-Galaxies模型下星系的多波段光谱

The SED of Present-day L-Galaxies from the Far-ultraviolet to the Far-infrared

  • 摘要: 星系形成的半解析模型是研究星系形成的重要工具, 当前主流的半解析模型不仅可以重现许多观测的星系性质, 也可以用来预言今后可能的大规模巡天观测结果. 使用L-Galaxies半解析模型生成星系的恒星形成历史, 考虑尘埃吸收以及再辐射, 结合基于SKIRT (Stellar Kinematics Including Radiative Transfer)辐射转移过程的机器学习模型starduster, 预测星系的多波段能谱分布. 结果显示starduster模型的尘埃消光略微不足, 导致在紫外及光学波段亮度略高于观测数据, 在更长的红外波段, starduster较好地复现了亮端的星系数目, 不过在暗端处稍显不足. 同时, 把经验的尘埃消光结合红外的能谱模板作为经验模型, 也可以得到从远紫外到远红外的光度函数. 经验模型表现出良好的尘埃消光效果, 并且其总体红外光度函数与观测结果相符. 虽然由于模板的观测数据限制, 无法完全重现暗端星系的数量, 但经验模型能够较好地预测红外各个波段的光度函数.

     

    Abstract: The semi-analytical model of galaxy formation in L-Galaxies has successfully predicted many galaxy properties. In this paper, we use L-Galaxies to simulate physical results such as the star formation history of galaxies. Considering the dust attenuation and re-radiation features, combined with the results SKIRT (Stellar Kinematics Including Radiative Transfer) radiative transfer simulation as the training data of the deep learning model starduster, we can predict galaxies' multi-band spectral energy distribution. The dust extinction of starduster is slightly insufficient, resulting in mildly higher than the observation data from FUV (far-ultraviolet) to optical, and at the longer wavelength, the number density of galaxies at the bright end is well reproduced, but under-predict the number of faint galaxies slightly. However, taking the empirical dust extinction combined with the infrared spectral energy distribution template as the empirical model to obtain the luminosity function from the FUV to the FIR (far infrared), the dust attenuation effect is quite good. And we find it in excellent agreement with observation at the UV (ultraviolet) band. Except that the number of galaxies at the faint end cannot be reproduced well, the luminosity functions at infrared are predicted accurately.

     

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