The evolution of galaxy in X-ray galaxy groups and clusters

星系团相当于各个星系生存和成长的城镇。我的研究是基于寻找新的星系团和研究它们所包含的星系。我利用名为“牛顿”和“钱德拉”的太空x射线天文台实现了这一目标，它们捕捉到与星系团相关的热气体云的图像。x射线气体中所含的热量是星系团质量的一个线索——就像一个质量“标签”——它类似于阅读毛衣上的标签，计算出它将有多大。然后，我使用各种各样的望远镜——从地面到太空的光学和红外望远镜——来研究每个星团中每个星系的“生命史”。结果是一幅巨大的星系属性变化图（大-小，老-年轻），每一个都与一个星系团相连，每个星系团都有一个标签，告诉我们它的质量。为了实现这一目标，我和我的研究生们正在与一个庞大的国际天文学家团队合作；就像全国人口普查告诉我们我们国家的趋势一样，这个“星系普查”告诉我们宇宙是如何变成今天的样子的。

Clusters of galaxies are equivalent to the towns and cities in which individual galaxies live and grow. My research is based upon finding new galaxy clusters and studying the galaxies they contain. I achieve this using space borne X-ray observatories - named "Newton" and "Chandra" - which capture images of the hot clouds of gas associated with galaxy clusters. The heat contained in the X-ray gas is a clue to how massive the galaxy cluster is - like a mass "label" - it is similar to reading the label on a sweater and working out how big it will be. I then use a wide variety of telescopes - in the optical and infrared, from ground and space - to study the "life history" of each galaxy in each cluster. What results is a huge map of changing galaxy properties (big-small, old-young) each attached to a galaxy cluster, and each cluster with a label telling us how massive it is. To achieve this, my graduate students and I are working with a large, international team of astronomers; just like the national census tells us abouts trends in our nation, this "galaxy census" tells us about how the universe came to look like it does today.