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標題: | 由觀測資料對暗能純量場之約束與比較 Confronting Quintessence and Phantom Dark Energy with Observational data |
作者: | Pao-Yu Wang 王寶瑜 |
指導教授: | 陳丕燊(Pisin Chen) |
關鍵字: | 暗能,模型,純量場,觀測資料, dark energy,tracker,attractor,quintessence,phantom,observation,data, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 1998年,觀察超新星爆炸的兩組人馬發現了現在的宇宙正處於加速膨脹,這發現 讓他們拿到了諾貝爾獎。這代表宇宙中必須有另一特殊的能量,稱為暗能,具有 強烈的負壓力以來推動宇宙加速。自此,人們提出許多暗能模型嘗試著想解釋這樣的加速現象;並且這些模型可以經由現在的觀測資料做檢驗。除了宇宙常 數,最受歡迎的模型之一是一純量場暗能;這種模型有解的”吸引”現象,讓他可 以部分程度的減輕宇宙巧合的問題。其中,Quintessence和Phantom都是純量場暗 能的種類,分別具有狀態函數大於-1和小於-1的性質。在這篇論文中,我將呈現 我們的工作:由觀測資料來約束與比較數種不同的純量場暗能模型,而我們討 論的模型都具有上述”吸引”的特性,也就是初始條件在現在顯得不重要。由最新 的超新星觀測、宇宙微波背景輻射和電漿震盪觀測數據,我們得到模型的參數 最佳值和限制範圍,發現現在的觀測傾向壓低模型的動態性質。不同的模型透 過goodness-of-fit和information criteria,宇宙常數仍然是現在觀測下最好的模型, 但也可以由比較看出觀測傾向狀態函數w < −1. In 1998, two groups studying supernovae have made a Nobel-Prize discovery, that the universe is under accelerating expansion. This suggests a substance, called dark energy, with strong negative pressure required to explain the acceleration. Numeral models have been proposed in order to explain the nature of dark energy, and they have to be tested with observations. Apart from ΛCDM, one type of promising dark energy candidate is scalar-field dark energy. Some of the scalar-field dark energy have attractor property that can alleviate cosmic coincidence problem. Quintessence and phantom are both scalar- field dark energy, with w > −1 and w < −1, respectively. This thesis is a work on confronting scalar-field dark energy models with current observations. The models we have considered are tracker quintessence and attractor/tracker phantom with several po- tential forms, which are all insensitive to initial conditions. While observation data come from latest SNIa, CMB and BAO, we obtain the best-fit and constraints on parameters for each model, showing that current observations limit dynamical behavior. By assess- ing Goodness-of-Fit and information criteria of models, it shows that ΛCDM is still the most preferred. Furthermore, current data favors phantom with w < −1 than quintessence with w > −1. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/66288 |
全文授權: | 有償授權 |
顯示於系所單位: | 物理學系 |
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