七單元宇宙微波陣列望遠鏡AMiBA及 其觀測所得之星系團性質比例關係

Abstract

李遠哲宇宙微波陣列望遠鏡(AMiBA)是一項專注在觀測宇宙微波背景輻射(CMB)之次級效應，包含Sunyaev-Zel'dovich效應(SZE)的實驗計畫。SZE不隨紅位移變化的特性使我們得以偵測遙遠的星系團，後者是了解宇宙大尺度形成演化的重要工具。在這篇論文裡我們將討論如何校正及解決於七單元AMiBA運作過程中所發生的關鍵問題。我們也將呈現第一個觀測年度的科學成果，主要聚焦在星系團的性質比例關係上。 AMiBA是一個共平面的干涉儀，在啟用的第一階段是由七座0.6米的天線及94 GHz的接收機組成六角形緊緻對稱的陣列組態。AMiBA擁有一個六足的驅動基座，因此望遠鏡指向修正模型相當獨特。在望遠鏡現場我們已進行了詳細的測試與校正，包括量測指向誤差，天線集光碟的波型，系統溫度及效率，天線指向的一致性，以及地面雜訊。所有系統誤差皆控制到可接受的精確度。此外我們也將討論觀測策略及資料處理。 2007年，AMiBA觀測六個高質量的Abell星系團並且偵測到它們的SZE。我們探討這些星系團的性質比例關係，包括積分Compton-y參數Y2500對於由X射線觀測所得之氣體溫度Te，總質量M2500，以及全頻譜X射線光度LX的關係。除了Y2500對LX的關係以外，我們的觀測結果皆與理論預測和其它已發表的研究吻合，而Y2500對LX的關係還需要更進一步的調查才能給出較佳的物理詮釋。我們的結果不僅驗證了AMiBA計畫，同時也支持我們已知對星系團的了解。

The Y.T. Lee Array for Microwave Background Anisotropy (AMiBA) is an experiment dedicated to observe the secondary signals in the cosmic microwave background (CMB), including the Sunyaev-Zel'dovich Effect (SZE). The redshift independence of the SZE enables the direct detection of distant galaxy clusters which are effective cosmological probes to the evolution of structure formation. In this dissertation we discuss how we calibrated and solved several key issues during the operation of 7-element AMiBA. We also present the science results of the first-year observation, in which we mainly focus on the scaling relations of galaxy clusters. AMiBA is a coplanar interferometer whose first commissioned phase consisted of seven 0.6-m antennas in a hexagonal close-packed configuration, with receivers operating at 94 GHz. It has a hexapod mount and thus an unique pointing model. We conducted the detailed testing and calibration on the site, including the measurement of pointing errors, the beam pattern of reflectors, the system temperature and efficiency, the radio alignment of antennas, and the ground pick-up. All systematics are controlled within acceptable accuracy. Observation strategies and data processing are also discussed. During 2007 six massive Abell clusters were observed and their SZEs were detected. We investigated the scaling relations of these clusters, relating the integrated Compton-$y$ parameter $Y_{2500}$ to X-ray derived gas temperature $T_{mathrm{e}}$, total mass $M_{2500}$, and bolometric luminosity $L_{mathrm{X}}$. Our results for the power-law index and normalization are both consistent with the self-similar model and other studies in literature except for the $Y_{2500}$--$L_{mathrm{X}}$ relation, for which physical explanation given though further investigation may be still needed. Our results provide not only confidence for AMiBA project but also supports to our understanding of galaxy clusters.