暗能量問題的數(shù)值研究
發(fā)布時(shí)間：2018-10-09 20:54
【摘要】：自1998年超新星觀測發(fā)現(xiàn)宇宙加速膨脹,暗能量問題已經(jīng)成為物理學(xué)界最受關(guān)注的研究課題之一。暗能量的起源、性質(zhì)都是謎。它向物理學(xué)家們提出了嚴(yán)峻的挑戰(zhàn),即所謂的“宇宙學(xué)常數(shù)問題”：為什么暗能量的能量密度這么小?為什么當(dāng)前暗能量的密度與物質(zhì)在同一個(gè)數(shù)量級上?為此,理論學(xué)家們作了非常多的努力,從各種不同的角度提出了很多暗能量理論模型,但是仍然沒能解決暗能量問題。 在沒有強(qiáng)有力的理論指導(dǎo)的情況下,我們需要轉(zhuǎn)向?qū)嶒?yàn),希望宇宙學(xué)觀測能夠提供更多解決暗能量問題的線索。幸運(yùn)的是,目前宇宙學(xué)家們已經(jīng)發(fā)展了超新星,重子聲學(xué)震蕩,宇宙微波背景輻射,弱引力透鏡等多種暗能量觀測手段。這些觀測進(jìn)一步確認(rèn)了宇宙加速膨脹,并極大地提高了暗能量的觀測精度。展望未來,宇宙學(xué)家們也在雄心勃勃地籌劃LSST, SKA等大型暗能量探測項(xiàng)目,希望通過更加精確的探測幫助我們揭開暗能量的神秘面紗。 研究生期間,我利用宇宙學(xué)觀測數(shù)據(jù)對暗能量問題作了一系列數(shù)值模擬研究。我們開發(fā)了穩(wěn)定可靠的宇宙學(xué)數(shù)值模擬程序,能夠方便地完成暗能量模型的數(shù)據(jù)擬合。我們的主要研究工作如下： 我們細(xì)致地研究了我的導(dǎo)師李淼老師提出的全息暗能量模型。理論上,我們提出了全息氣體模型；數(shù)值上,我們作了一系列工作,包括不同紅外截?cái)嗄Ｐ偷谋容^,相互作用與曲率的觀測限制,全息暗能量的推廣,以及全息暗能量與暗物質(zhì)相互作用問題。 我們也研究了其他一些暗能量模型。我們利用最新的觀測數(shù)據(jù)對九種暗能量模型與五種修改引力模型作了限制、比較,并重構(gòu)了修改引力模型中的宇宙結(jié)構(gòu)增長歷史。我們還研究了一類能夠在過去光錐上完全重構(gòu)宇宙學(xué)常數(shù)觀測的不均勻宇宙模型,并提出利用宇宙年齡檢驗(yàn)來鑒別這類模型。 我們詳細(xì)研究了暗能量重構(gòu)課題。我們利用紅移分段,多項(xiàng)式差值等參數(shù)化手段仔細(xì)分析了Constitution, Union2以及SNLS3超新星數(shù)據(jù)。對宇宙膨脹歷史、暗能量狀態(tài)方程、以及暗能量動(dòng)力學(xué)演化作了詳細(xì)的討論研究。我們發(fā)現(xiàn),Constitution數(shù)據(jù)傾向于動(dòng)力學(xué)演化的暗能量,而Union2與SNLS3數(shù)據(jù)則更傾向于宇宙學(xué)常數(shù)。 此外,我們還探討了幾個(gè)與暗能量相關(guān)的小問題。我們初步研究了超新星數(shù)據(jù)的張力問題。我們還研究了一些古老天體帶來的宇宙年齡問題,并試圖通過引入暗能量與暗物質(zhì)相互作用來化解這一問題,我們發(fā)現(xiàn)宇宙年齡問題能夠得到些許緩和,但仍然沒有完全解決。最后,我們還用參數(shù)化重構(gòu)的方法研究了暗能量對宇宙命運(yùn)的影響,我們發(fā)現(xiàn),在最壞的情況下,宇宙距離大撕裂的時(shí)間為16.7Gyr。
[Abstract]:Since supernova observations in 1998 found that the universe is expanding rapidly, dark energy has become one of the most concerned topics in physics. The origin and nature of dark energy are riddles. It poses a serious challenge to physicists, the so-called "cosmological constant problem": why is the energy density of dark energy so small? Why is the current density of dark energy on the same order of magnitude as matter? For this reason, theorists have made a lot of efforts and put forward a lot of dark energy theoretical models from different angles, but they still can not solve the problem of dark energy. In the absence of strong theoretical guidance, we need to turn to experiments in the hope that cosmological observations will provide more clues to the problem of dark energy. Fortunately, cosmologists have developed a variety of dark energy observations such as supernovae, baryon acoustic oscillations, cosmic microwave background radiation, and weak gravitational lensing. These observations further confirm the accelerating expansion of the universe and greatly improve the observation accuracy of dark energy. Looking ahead, cosmologists are also planning ambitious dark energy exploration projects such as LSST, SKA, hoping to help us unravel the mystery of dark energy through more accurate detection. As a graduate student, I made a series of numerical simulations of dark energy using cosmological observations. A stable and reliable numerical simulation program for cosmology has been developed, which can easily fit the dark energy model. Our main research work is as follows: we have carefully studied the holographic dark energy model proposed by my teacher Li Miao. In theory, we propose a holographic gas model, numerically, we do a series of work, including the comparison of different infrared truncation models, the observation limitation of interaction and curvature, the generalization of holographic dark energy. And the interaction between holographic dark energy and dark matter. We have also studied other dark energy models. We use the latest observational data to limit nine dark energy models and five modified gravitational models, and reconstruct the growth history of the universe structure in the modified gravity model. We also study a class of inhomogeneous cosmological models which can completely reconstruct cosmological constant observations on past optical cones and propose to use cosmic age test to identify these models. We study the problem of dark energy reconstruction in detail. Constitution, Union2 and SNLS3 supernova data are carefully analyzed by means of red-shift segmentation, polynomial difference and other parameterization methods. The history of expansion of the universe, the equation of state of dark energy, and the dynamic evolution of dark energy are discussed in detail. We find that the Union2 and SNLS3 data tend to be more cosmological constants, while the Union2 data tend to be the dark energy of dynamical evolution. In addition, we discuss several small problems related to dark energy. We have studied the tension problem of supernova data. We also study the cosmic age problem brought about by some ancient celestial bodies and try to solve this problem by introducing dark energy and dark matter interaction. We find that the cosmic age problem can be alleviated slightly but not completely solved. Finally, we also study the influence of dark energy on the fate of the universe by parameterized reconstruction. We find that in the worst case, the time of large distance tearing is 16.7 Gyr.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2012
【分類號】：P159
本文編號：2260757
[Abstract]:Since supernova observations in 1998 found that the universe is expanding rapidly, dark energy has become one of the most concerned topics in physics. The origin and nature of dark energy are riddles. It poses a serious challenge to physicists, the so-called "cosmological constant problem": why is the energy density of dark energy so small? Why is the current density of dark energy on the same order of magnitude as matter? For this reason, theorists have made a lot of efforts and put forward a lot of dark energy theoretical models from different angles, but they still can not solve the problem of dark energy. In the absence of strong theoretical guidance, we need to turn to experiments in the hope that cosmological observations will provide more clues to the problem of dark energy. Fortunately, cosmologists have developed a variety of dark energy observations such as supernovae, baryon acoustic oscillations, cosmic microwave background radiation, and weak gravitational lensing. These observations further confirm the accelerating expansion of the universe and greatly improve the observation accuracy of dark energy. Looking ahead, cosmologists are also planning ambitious dark energy exploration projects such as LSST, SKA, hoping to help us unravel the mystery of dark energy through more accurate detection. As a graduate student, I made a series of numerical simulations of dark energy using cosmological observations. A stable and reliable numerical simulation program for cosmology has been developed, which can easily fit the dark energy model. Our main research work is as follows: we have carefully studied the holographic dark energy model proposed by my teacher Li Miao. In theory, we propose a holographic gas model, numerically, we do a series of work, including the comparison of different infrared truncation models, the observation limitation of interaction and curvature, the generalization of holographic dark energy. And the interaction between holographic dark energy and dark matter. We have also studied other dark energy models. We use the latest observational data to limit nine dark energy models and five modified gravitational models, and reconstruct the growth history of the universe structure in the modified gravity model. We also study a class of inhomogeneous cosmological models which can completely reconstruct cosmological constant observations on past optical cones and propose to use cosmic age test to identify these models. We study the problem of dark energy reconstruction in detail. Constitution, Union2 and SNLS3 supernova data are carefully analyzed by means of red-shift segmentation, polynomial difference and other parameterization methods. The history of expansion of the universe, the equation of state of dark energy, and the dynamic evolution of dark energy are discussed in detail. We find that the Union2 and SNLS3 data tend to be more cosmological constants, while the Union2 data tend to be the dark energy of dynamical evolution. In addition, we discuss several small problems related to dark energy. We have studied the tension problem of supernova data. We also study the cosmic age problem brought about by some ancient celestial bodies and try to solve this problem by introducing dark energy and dark matter interaction. We find that the cosmic age problem can be alleviated slightly but not completely solved. Finally, we also study the influence of dark energy on the fate of the universe by parameterized reconstruction. We find that in the worst case, the time of large distance tearing is 16.7 Gyr.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2012
【分類號】：P159
【參考文獻(xiàn)】
相關(guān)期刊論文 前3條
1 ;Holographic Gas as Dark Energy[J];Communications in Theoretical Physics;2009年01期
2 ;Comparison of dark energy models:A perspective from the latest observational data[J];Science China(Physics,Mechanics & Astronomy);2010年09期
3 ;Dark energy and fate of the Universe[J];Science China(Physics,Mechanics & Astronomy);2012年07期
，本文編號：2260757
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