Chemical Abundances in the Intergalactic Medium: Evolution and Constraints on Feedback From Galaxy Formation

Simcoe博士将使用智利麦哲伦望远镜上的仪器研究宇宙历史早期星系间气体中碳和氧的积累，在星系形成大部分恒星之前和期间。 这些“重”化学元素在恒星内部产生，并在恒星死亡时释放到星际气体中。 在年轻的星系中，它们的活动核和剧烈的恒星诞生都可以将富含重元素的气体喷射到星系际空间。 因此，星系际气体中的碳和氧的数量可以追溯到星系的形成。 高度电离的碳和氧的最强光谱线在紫外线。 但在遥远类星体的光谱中，宇宙膨胀意味着我们在红移因子1+z的波长上观察到这些线，因此它们在可见光甚至红外波长上都可以看到。 Simcoe博士将采用高质量的光谱来推导位于我们和红移范围为2.5z4.5的发光类星体之间的气体的碳和氧丰度。 对南半球麦哲伦望远镜可获得的14个z5.8已知类星体的研究将是FIRE红外光谱仪的第一个科学项目，该项目是Simcoe博士在早期NSF资助下建造的。 FIRE应该准备在2009年底进入望远镜。 一名研究生将通过从事这个项目来接受培训。 Simcoe博士将继续通过麻省理工学院的UROP项目培训本科生;他已经通过这个项目指导了五名学生，其中四名是物理科学代表性不足的群体的成员。 在FIRE的早期科学项目中，Simcoe博士和他的团队将优化还原和分析工具，并将其提供给麦哲伦用户社区。

Dr. Simcoe will use instruments on the Magellan telescopes in Chile to study the buildup of carbon and oxygen in the intergalactic gas early in cosmic history, before and during the period when the galaxies made most of their stars. These 'heavy' chemical elements are produced inside stars, and released into interstellar gas as the stars die. In young galaxies, both their active nuclei and violent starbirth can eject heavy-element-rich gas into intergalactic space. Thus the amount of carbon and oxygen in the intergalactic gas traces the formation of the galaxies. The strongest spectral lines of highly-ionized carbon and oxygen are in the ultraviolet. But in the spectra of distant quasars, cosmic expansion means that we observe these lines at wavelengths longer by the redshift factor 1+z, so they are seen at visible or even infrared wavelengths. Dr. Simcoe will take high-quality optical spectra to derive carbon and oxygen abundances for gas that lies between us and luminous quasars in the redshift range 2.5z4.5. Studies of the 14 known quasars with z5.8 that are accessible from the Southern-hemisphere Magellan telescopes will be a first science project for the FIRE infrared spectrograph, which Dr. Simcoe has built under an earlier NSF grant. FIRE should be ready to go to the telescope in late 2009. A graduate student will be trained by working on this project. Dr. Simcoe will continue to train undergraduate students through MIT's UROP program; he has already mentored five students through this program, four of whom were members of groups under-represented in the physical sciences. During this early science project with FIRE, Dr. Simcoe and his team will optimize the reduction and analysis tools, and make them available to the Magellan user community.