Galaxy spectral energy distributions (SEDs) remain among the most challenging yet informative quantities to reproduce in simulations due to the large and complex mixture of physical processes that shape the radiation output of a galaxy. With the increasing number of surveys utilising broadband colours as part of their target selection criteria, the production of realistic SEDs in simulations is necessary for assisting in survey design and interpretation of observations. The recent success in reproducing the observed luminosity functions (LF) from far-UV to far-IR, using the state-of-the-art semi-analytic model \shark\ and the SED generator \prospect, represents a critical step towards better galaxy colour predictions. We show that with \shark\ and \prospect\ we can closely reproduce the optical colour distributions observed in the panchromatic GAMA survey. The treatment of feedback, star formation, central-satellite interactions and radiation re-processing by dust are critical for this achievement. The first three processes create a bimodal distribution, while dust attenuation defines the location and shape of the blue and red populations. While a naive comparison between observation and simulations displays the known issue of over-quenching of satellite galaxies, the introduction of empirically-motivated observational errors and classification from the same group finder used in GAMA greatly reduces this tension. The introduction of random re-assignment of $\sim 15\%$ of centrals/satellites as satellites/centrals on the simulation classification closely resembles the outcome of the group finder, providing a computationally less intensive method to compare simulations with observations.

中文翻译：

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从静止坐标系光度函数到观察者坐标系颜色分布：应对宇宙学模拟中的下一个挑战

由于塑造星系辐射输出的物理过程的大量复杂混合，星系光谱能量分布 (SED) 仍然是模拟中最具挑战性但信息量最大的量之一。随着使用宽带颜色作为其目标选择标准的一部分的调查越来越多，在模拟中产生真实的 SED 对协助调查设计和观察解释是必要的。最近使用最先进的半解析模型 \shark\ 和 SED 生成器 \prospect 在从远紫外到远红外再现观察到的光度函数 (LF) 方面取得了成功，代表了迈向更好的关键一步星系颜色预测。我们表明，使用 \shark\ 和 \prospect\，我们可以精确地再现在全色 GAMA 调查中观察到的光学颜色分布。对反馈、恒星形成、中央卫星相互作用和尘埃辐射再处理的处理对于这一成就至关重要。前三个过程创建了双峰分布，而尘埃衰减定义了蓝色和红色种群的位置和形状。虽然观察和模拟之间的天真比较显示了卫星星系过度淬火的已知问题，但从 GAMA 中使用的同一组发现者引入的经验性观察误差和分类大大减少了这种紧张。