【摘要】：近些年來(lái)許多天文觀(guān)測(cè)結(jié)果表明宇宙正在加速膨脹,科學(xué)家們用一種被稱(chēng)為“暗能量”的奇異物質(zhì)來(lái)解釋這一現(xiàn)象。暗能量在宇宙中幾乎均勻分布,它最大的特點(diǎn)就是壓強(qiáng)為負(fù)。目前,人們已經(jīng)建立了各種各樣的暗能量模型。 由于暗能量模型越來(lái)越多,區(qū)別不同的暗能量模型很重要。本文運(yùn)用幾何方法,包括Statefinder和om,甄別純動(dòng)能K-essence和LCDM暗能量模型。我們作出平面演化圖,發(fā)現(xiàn)在68.3%置信區(qū),當(dāng)時(shí),Statefinder不能區(qū)別純動(dòng)能K-essence和LCDM暗能量模型。om也被廣泛的用來(lái)區(qū)別不同的暗能量模型,然而本文發(fā)現(xiàn),om不能區(qū)別純動(dòng)能K-essence和LCDM暗能量模型。 對(duì)冪形式的K-essence模型進(jìn)行了詳細(xì)的相空間分析,我們發(fā)現(xiàn)臨界點(diǎn)可以分成三類(lèi):臨界點(diǎn)不穩(wěn)定但模型穩(wěn)定;臨界點(diǎn)和模型都穩(wěn)定;臨界點(diǎn)穩(wěn)定但模型不穩(wěn)定。根據(jù)宇宙學(xué)理論,第一種和第三種情況都是沒(méi)有意義的,盡管可能存在宇宙晚期吸引子。為了研究宇宙最后可能的狀態(tài),不僅臨界點(diǎn)應(yīng)是穩(wěn)定的,模型也應(yīng)該是穩(wěn)定的。臨界點(diǎn)和模型都穩(wěn)定也可以分為兩種情況,一是宇宙不會(huì)出現(xiàn)加速膨脹;另外是宇宙有可能加速,有可能減速,有可能勻速,最后的狀態(tài)取決與勢(shì)能。同時(shí),僅僅研究臨界點(diǎn)的穩(wěn)定性是不夠的,還必需研究模型的穩(wěn)定性。
[Abstract]:In recent years, many astronomical observations have shown that the universe is expanding at an accelerated rate, and scientists have interpreted the phenomenon with a strange substance called "dark energy". Dark energy is almost uniformly distributed in the universe, and its greatest feature is that the pressure is negative. At present, various dark energy models have been established. Because there are more and more dark energy models, it is important to distinguish different dark energy models. In this paper, geometric methods are used, including Statefinder and om, to identify pure kinetic energy K-essence and LCDM dark energy models. We made the plane evolution diagram and found that in the 68.3% confidence region, at that time, Statefinder could not distinguish pure kinetic energy K-essence from LCDM dark energy model. Om is also widely used to distinguish different dark energy models. Om cannot distinguish between pure kinetic energy K-essence and LCDM dark energy model. A detailed phase space analysis of the power form K-essence model is carried out. We find that the critical points can be classified into three categories: the critical points are unstable but the model is stable; the critical points and the models are stable; the critical points are stable but the models are unstable. According to cosmology, the first and third cases are meaningless, although there may be late attractors in the universe. In order to study the last possible state of the universe, not only the critical point should be stable, but also the model should be stable. The stability of the critical point and the model can also be divided into two situations, one is that the universe does not appear accelerated expansion, the other is that the universe may accelerate, decelerate, or even, and the final state depends on the potential energy. At the same time, it is not enough to study the stability of the critical point, and it is necessary to study the stability of the model.
【學(xué)位授予單位】：河北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類(lèi)號(hào)】：P145.9

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