The chemistry of galaxies

在自下而上的星系形成图中，矮星系就像雪花，而巨型星系就像雪堆。要了解雪是如何形成和扩散的，我们应该把注意力集中在雪花的结构和分布上。要了解雪是如何积累的，重点应该转移到雪堆上。在此逻辑指引下，申请人建议在下一个拨款期集中研究形成恒星的矮星系和巨型螺旋星系的凸起和盘状。在近红外波段对矮星进行有针对性的研究，将有助于我们更深入地了解它们是如何形成的，并改进一种新的工具来绘制它们在整个宇宙中的分布。对它们的分布和局部运动的分析将使我们能够描绘出局部星系片的轮廓。局部星系片是一个高度扁平的结构，银河系和其他1500万光年外的星系都是在这个结构中发现的，但我们对它知之甚少。通过对螺旋的研究，我们将有可能了解气体流动是如何影响进化的。与此同时，这项工作将带来一种工具，可以可靠地测量宇宙最远处星系的化学富集。

In the bottom-up picture of galaxy formation, dwarf galaxies are like snowflakes and giant galaxies are like snowdrifts.  To learn about how the snow forms and disperses, attention should be focussed on the structure and distribution of the snowflakes.  To learn about how snow accumulates, the focus should shift to the snowdrifts.  Guided by this logic, the applicant proposes to focus studies over the next grant period on star-forming dwarf galaxies and the bulges and disks of giant spiral galaxies.   Pointed studies of dwarfs in the near-infrared will lead to a deeper understanding of how they formed, and refinement of a new tool to map their arrangment throughout the universe.  Analyses of their distribution and motions locally will enable characterization of the profile of the Local Sheet of Galaxies, a highly flattened structure within which the Milky Way and all other galaxies out to 15 million light years are found yet about which little is known.  From studies of spirals, it will be possible to glean how flows of gas have affected evolution.  At the same time, the work will lead to a tool to reliably measure the chemical enrichment of galaxies in the farthest reaches of the universe.