教師資料查詢 | 類別: 研究報告 | 教師: 劉國欽 LIOU GUO CHIN (瀏覽個人網頁)

標題:天文觀測與暗黑能量模型之限制
學年97
學期1
出版(發表)日期2009/01/01
作品名稱天文觀測與暗黑能量模型之限制
作品名稱(其他語言)Constraining Dark Energy Models through Astrophysical Observations
著者劉國欽
單位淡江大學物理學系
描述計畫編號NSC97-2112-M032-007-MY3;研究期間200908~201007;研究經費633,000
委託單位行政院國家科學委員會
摘要現今存在著不少暗黑能量的模型來解釋宇宙加速膨脹的現象.在這裡,我提議使用宇 宙學上的觀測來限制各種暗黑能量的模型以及模型中的參數.目前想要限制的模型包 含了:(1) Interacting Holographic Model,(2) Modified Gravity theory 以及 (3) Torsion cosmology.在Interacting Holographic 的模型中,有兩個參數可用來描寫這個模型,一 個是暗黑能量與暗黑物質之間的作用強度,另一個是cutoff尺度的大小.至於Modified Gravity,儘管仍存在著許多理論,我們可以用兩個參數來描寫他們:一個是anisotropic stress tensor,這在廣義相對論裡是零,另一個是一般化的牛頓重力常數. 在Torsion的 模型中,也有不同的描寫參數,例如Torsion的質量以及動能密度等等. 用來印證暗黑能量模型的觀測必須是對於兩種物理量敏感的觀測:一是宇宙膨脹速率, 一是物質密度微擾的成長.在這個工作,我提議使用四種觀測:(1)宇宙背景輻射,包 含了其溫度的非均向性與極化現象的功率譜以及Integrated Sachs-Wolfe效應.所謂的 Integrated Sachs-Wolfe效應,是由CMB 光子在移動到觀測者的過程中重力位能有變化 所引起.(2) Ia 型的超新星給予我們距離以及紅位移的關係.(3)星係團的密度. 有許 多觀測可以使用,這裡我們提議Sunyaev-Zeldovich 的觀測,因為可以結合國內 AMiBA 的計畫.(4)物質的功率譜,可由星係探測取得. 這個工作的最終目的,是篩選暗黑能量的模型以及限制模型中的參數.而這個工作也 加強了國內高能理論與AMiBA觀測計畫的聯繫. There are many dark energy models to explain the accelerating expansion of the Universe. Here, I propose to study various dark energy models through cosmological observations. Proposed dark energy models include (1) Interacting Holographic model, (2) Modified gravity theory and (3) Torsion cosmology. In the interacting holographic model, I propose to study two parameters, the interacting strength between dark energy and dark matter, and the cutoff scale. For modified gravity, though various models exist, we can parameterize all the models just by two parameters: anisotropic stress tensor, which is zero in General Relativity, and generalized Newtonian gravitation constant. There are some parameters in torsion too, for example, mass parameter and kinetic energy density of the torsion. These parameters can be studied through cosmological observations. Useful cosmological observations for studying dark energy have mainly two observation consequence: it affects the expansion rate of universe and growth rate of the density perturbations. Therefore, I propose four observations in near future: (1) Cosmic Microwave Background (CMB), including its power spectra of temperature anisotropy and polarization, and Integrated Sachs-Wolfe effect, which arises from the time variation of scalar metric perturbations. (2) Supernova Type Ia, the standard candle in the Universe to determine the luminosity distance vs. redshift relation. (3) Galaxy cluster counting by Sunyaev-Zeldovich effect observations. It is related to AMiBA project in Taiwan. (4) Matter power spectrum from galaxy survey. The final goal for this work is to filter the dark energy models and to give constraint on these parameters in each model. And this works connects the theoretical high energy group in Taiwan and AMiBA project.
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