Assembling the big picture of nearby galaxies

星系是宇宙的基石，是恒星和行星诞生的地方。星系的内部生命是复杂的：恒星由稠密的冷气体形成，在有限的生命期内将氢融合成氦和更重的元素，然后死亡，将一些处理过的物质返回到太空，在那里再次开始循环。恒星、星际气体和尘埃、星系周围的暗物质晕以及位于星系中心的巨大黑洞之间存在着复杂的相互作用。新星星形成的速率取决于气体的物理性质，而气体的物理性质又取决于星星形成的过去历史，这影响着中心黑洞，也可以受到中心黑洞的影响。在建立星系的故事时，重要的问题包括模型是否可以重建独特的过去历史，星系内新恒星的形成如何变化，以及如何最好地测量星系的质量和星星形成。不同星系组成部分的压力、温度和密度的巨大变化意味着星系的不同部分吸收和发射许多不同波长的光。虽然天文学家以前倾向于专注于在特定波长下进行的观测，但现在很明显，我们需要一种多波长方法来收集星系如何达到目前状态多样性的全貌。 在附近的星系中，现有的观测可以细致地探测这些复杂生态系统的现在和过去，但前提是我们能够找到新的更好的方法来管理和利用数据。该计划将开发工具和技术来比较星系的内部结构，以及描述恒星，气体，尘埃，黑洞和暗物质之间相互作用的日益复杂的模型。 这将使我们能够推导出附近星系的详细历史，这是理解银河系和我们自己在宇宙中的位置的重要组成部分。该计划开发的工具和培训将可转移到其他应用中，并使天体物理学家能够为“大数据”科学的其他领域做出贡献。

Galaxies are the building blocks of the universe, the place where stars and planets are born. The inner life of galaxies is complex: stars are formed from dense, cold gas, spend their finite lifetimes fusing hydrogen into helium and heavier elements, and then die, returning some of the processed material to space where the cycle begins again. There is a complicated interplay between stars, interstellar gas and dust, the haloes of dark matter that surround galaxies and the giant black holes that live at their centres. The rate of new star formation depends on the physical properties of the gas, which in turn depend on the past history of star formation, which affects and can be affected by the central black hole. In establishing the stories of galaxies, important questions include whether models can reconstruct unique past histories, how the formation of new stars varies within galaxies, and how the mass and star formation of galaxies can best be measured. The huge variations in pressure, temperature, and density in the various galaxy components mean that different parts of galaxies absorb and emit light at many different wavelengths. While astronomers previously tended to specialize in observations made at a particular wavelength, it is now clear that we need a multi-wavelength approach to assemble the full picture of how galaxies arrived at their present diversity of states. In nearby galaxies the available observations can probe both the present and past of these complex ecosystems in exquisite detail, but only if we can find new and better ways to manage and exploit the data. This program will develop the tools and techniques to compare the internal structures of galaxies to each other and to the increasingly-sophisticated models which describe the interplay between stars, gas, dust, black holes, and dark matter. This will enable the derivation of detailed histories of nearby galaxies, an important part of the quest to understand the Milky Way's---and our own---place in the universe. The tools and training developed in this program will be transferable to other applications and enable astrophysicists to contribute to other areas of "Big Data" science.