利用伽普立金氣體考慮宇宙暴漲前的拓樸缺陷時期

Abstract

我們用一個簡單現象學上的模型來描述在暴漲時期之前的兩種宇宙拓樸缺陷：(1)以疇壁主的緩慢加速膨脹，和(2)以宇宙弦為主的等速度膨脹。此時期的存在可修正宇宙背景輻射在標準宇宙模型所預測的頻譜和觀測頻譜之間在低模態上的不吻合。考慮宇宙裡的物質為理想流體伽普立金氣體，能提供拓樸缺陷到暴漲時期間轉換的現象學上等效描述。 此外，我們也針對我們提出的模型並利用博戈留波夫轉換來預測重力子在宇宙膨脹產生的數量以求得重力波頻譜。而部分波段有可能在不久的未來被現在一些準備中的探測器偵測到。

We present a simple toy model corresponding to a network of frustrated topological defects of domain walls or cosmic strings that exist previous to the standard slow-roll inflationary era of the universe. Such a network (i) can produce a slower inflationary era than that of the standard scenario if it corresponds to a network of frustrated domain walls or (ii) can induce a vanishing universal acceleration; i.e., the universe would expand at a constant speed, if it corresponds to a network of frustrated cosmic strings. Those features are phenomenologically modeled by a Chaplygin gas that can interpolate between a network of frustrated topological defects and a de Sitter-like or a power-law inflationary era. We show that this scenario can alleviate the quadruple anomaly of the cosmic microwave background spectrum. Using the method of the Bogoliubov coefficients, we obtain the spectrum of the gravitational waves as would be measured today for the whole range of frequencies. We comment on the possible detection of this spectrum by the planned detectors like BBO and DECIGO.