本文關鍵詞：有相互作用的廣義Chaplygin氣體動力學分析及參數(shù)擬合　出處：《上海師范大學》2016年碩士論文　論文類型：學位論文

  更多相關文章： 宇宙加速 GCG 相互作用 參數(shù)擬合

【摘要】：對Ia型超新星的觀測發(fā)現(xiàn)宇宙是加速膨脹的,宇宙加速膨脹即尺度因子的二階導數(shù)a大于0,由弗里德曼方程可知,要使a大于0則需要場方程右邊多出一個提供負壓強的部分。這個負壓強不僅抵消了物質(zhì)引力產(chǎn)生的減速效果還進一步地使宇宙加速膨脹,這部分稱為暗能量。研究表明宇宙學常數(shù)和quintessence場可作為暗能量的候選者。然而觀測發(fā)現(xiàn)暗物質(zhì)與暗能量在當前量級相同,此即引出了巧合性問題,即為什么當前宇宙的暗物質(zhì)和暗能量量級相同,是巧合還是必然?基于這個問題,追蹤場、K-sessence、Chaplygin氣體等模型被提了出來,閱讀文獻時發(fā)現(xiàn)如果用上述幾個模型對冷暗物質(zhì)做一個耦合則會一定程度上緩解巧合性問題。會得出一些與初始條件無關的宇宙學演化模式。而考慮Chaplygin氣體與冷暗物質(zhì)部分相互作用時發(fā)現(xiàn)其不僅能緩解巧合性問題,還可以統(tǒng)一暗物質(zhì)與暗能量,具體表現(xiàn)為宇宙早期a趨向于0時表現(xiàn)出暗物質(zhì)的性質(zhì),晚期時ω趨向于-1(ω為態(tài)方程參數(shù))表現(xiàn)出暗能量的性質(zhì)。本文在解決了自治系統(tǒng)奇性的基礎上,對GCG與DM相互作用項最簡單的幾種情況進行了討論。分別是及Q=-3βHp8(β為無量綱參數(shù),ρm,ρ8,ρtot分別表示物質(zhì)密度,Chaplygin氣體密度和物質(zhì)密度與Chaplygin氣體密度之和)。分別對各自的自治系統(tǒng)的性質(zhì)進行了分析,討論了臨界點處的性質(zhì),得出了符合宇宙加速膨脹的結果,并與標準的ACDM模型做了比較。
[Abstract]:Observations of type Ia supernovae discovered that the universe is accelerating expansion, the accelerated expansion of the universe is the two derivative of the scale factor of a is greater than 0, by the Freedman equation, to make a more than 0 to the right of a multi field equation provides negative pressure part. The negative pressure not only offset the effect of gravitational deceleration produced the further that the accelerated expansion of the universe, this part is called dark energy. The results indicate that the cosmological constant and the quintessence field can be used as a candidate of dark energy. However, the observation that dark matter and dark energy in the same order of magnitude, which leads to the coincidence problem, that is why the current cosmic dark matter and dark energy in the same order that is a coincidence or a necessity? Based on this problem, tracking field, K-sessence, Chaplygin gas model is proposed, the reading of the literature found that if a coupling of cold dark matter with the model He will to some extent alleviate the coincidence problem. Come about the initial conditions of cosmological evolution mode. And considering the Chaplygin gas and the cold dark matter interaction and found that it can not only alleviate the coincidence problem, can also unified the dark matter and dark energy, the specific performance of the early universe when a tends to 0 the nature of dark matter, late tend to -1 (omega Omega for equation of state parameters) exhibit the properties of dark energy. In the base of solving the singular autonomous system, GCG on the interaction between DM and the most simple situations are discussed respectively. And Q=-3 Hp8 (beta beta the dimensionless parameters, P M, P 8, P tot respectively matter density, Chaplygin density and the material density and the density of Chaplygin gas and) respectively. The nature of their respective autonomous systems are analyzed, discussed the nature of the critical point, the character The result of the accelerated expansion of the universe is compared with the standard ACDM model.

【學位授予單位】：上海師范大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：P159

【參考文獻】

相關期刊論文 前1條

1 韋浩;;Cosmological Constraints on the Sign-Changeable Interactions[J];Communications in Theoretical Physics;2011年11期

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本文編號：1425393