Space Telescope Science Institute, Baltimore, MD 21218, USA.
Science. 2011 Nov 18;334(6058):948-52. doi: 10.1126/science.1209840.
The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of intergalactic gas, but its mass, heavy element enrichment, and relation to galaxy properties are poorly constrained by observations. In a survey of the outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we detected ubiquitous, large (150-kiloparsec) halos of ionized oxygen surrounding star-forming galaxies; we found much less ionized oxygen around galaxies with little or no star formation. This ionized CGM contains a substantial mass of heavy elements and gas, perhaps far exceeding the reservoirs of gas in the galaxies themselves. Our data indicate that it is a basic component of nearly all star-forming galaxies that is removed or transformed during the quenching of star formation and the transition to passive evolution.
星系周围介质（CGM）由星系外流和星系间气体的吸积提供，但它的质量、重元素丰度及其与星系性质的关系，观测数据还很难确定。在哈勃太空望远镜搭载的宇宙起源光谱仪对 42 个星系的外围进行的一项调查中，我们探测到了在恒星形成星系周围普遍存在的、规模巨大（150 千秒差距）的电离氧晕；我们发现，在那些恒星形成很少或没有的星系周围，电离氧要少得多。这种电离的 CGM 含有大量的重元素和气体，其质量也许远远超过星系本身的气体储量。我们的数据表明，它是几乎所有恒星形成星系的基本组成部分，在恒星形成的熄灭和向被动演化的转变过程中被去除或转化。
