利用观测数据研究宇宙的加速膨胀

发布时间：2018-02-12 08:22

本文关键词： 暗能量宇宙学加速膨胀减速因子　出处：《宁波大学》2013年硕士论文　论文类型：学位论文

【摘要】：Ia型超新星观测(SNIa)，重子声学振荡(BAO)和微波背景辐射(CMB)等天文观测表明我们的宇宙正处在一个加速膨胀的阶段。通常，人们认为宇宙中存在一种具有负压的暗能量从而导致了宇宙今天的加速膨胀。现有绝大部分暗能量模型都支持宇宙加速度应该还处在一个持续增大的阶段。利用低红移的SNIa和BAO观测数据以及CPL参数化模型，人们发现宇宙膨胀加速度很可能在过去不久已进入了减小阶段。一旦加入高红移的CMB数据，观测仍支持宇宙膨胀加速度在增大。这就表明低红移数据(SNIa和BAO)与高红移(CMB)数据可能存在某些不相容性。如果将曲率因子k作为一个自由参数，SNIa+BAO观测数据和SNIa+BAO+CMB观测数据将都支持宇宙膨胀加速度可能进入减小阶段。因此，曲率因子k有效的缓解了低红移数据与高红移数据之间的不相容问题。本文根据MCMC方法和CPL参数化模型，利用最新的观测数据重新探讨了宇宙减速因子的演化情况。观测数据包括来自Union2的超新星数据,来自WMAP7的CMB数据,以及来自4个不同的BAO项目的BAO数据。四个BAO项目分别来是6度视场星系巡天项目,斯隆数字巡天结合2度视场星系红移巡天的项目,Wigglez暗能量测量项目和重子振荡光谱测量项目。我们分别研究了减速因子在假定空间平坦和空间弯曲情形下的演化。当只考虑超新星或者超新星加上重子声学振荡时,除了来自WiggleZ暗能量测量项目的数据外,无论空间平坦还是空间弯曲,数据都支持宇宙现在膨胀的加速度是在减小，而当微波背景辐射的数据被考虑进去时，，结果则强烈的支持ΛCDM模型，而且宇宙膨胀的加速度仍然是在增大过程中。因此，最新数据表明考虑宇宙空间弯曲因素并不能有效的缓解SNIa+BAO与CMB数据之间的矛盾。
[Abstract]:Astronomical observations such as the Ia supernova observation, baryon acoustic oscillation (BAO) and microwave background radiation (CMB) indicate that our universe is at a stage of accelerating expansion. It is believed that there is a kind of dark energy with negative pressure in the universe, which leads to the accelerating expansion of the universe today. Most of the existing dark energy models support that the acceleration of the universe should be at a stage of continuous increase. Low-redshift SNIa and BAO observations and CPL parameterized models, It has been found that the expansion acceleration of the universe has probably entered a decreasing phase in the past few years. Once Gao Hong's CMB data are added, Observations still support an increase in the expansion acceleration of the universe. This suggests that there may be some incompatibility between the low redshift data (SNIa and AO) and the Gao Hong shift (CMBs) data. If the curvature factor k is taken as a free parameter, the SNIa BAO data and the SNIa may exist. The BAO CMB observations will all support the possibility that the expansion acceleration of the universe may enter a reduced phase. Curvature factor k effectively alleviates the incompatibility between low red shift data and Gao Hong shift data. Based on the MCMC method and the CPL parameterized model, the evolution of the cosmic deceleration factor is revisited with the latest observational data. The observed data include supernova data from Union2 and CMB data from WMAP7. And BAO data from four different BAO projects. The four BAO projects are the six Field of View Galaxy Survey Project. We study the evolution of the deceleration factor under the assumption of space flatness and spatial curvature, respectively, in conjunction with the Sloan Digital Sky Survey and the two dimensional field of view galaxies' red-shift survey projects, Wigglez dark energy measurement and baryon oscillatory spectral measurements, respectively. When only supernova or supernova is considered plus baryon acoustic oscillation, With the exception of data from the WiggleZ dark energy measurement project, whether the space is flat or curved, the data support that the expansion acceleration of the universe is now decreasing, and when the microwave background radiation data are taken into account, The results strongly support the CDM model, and the acceleration of cosmic expansion is still in the process of increasing. Therefore, the latest data show that considering space bending factors can not effectively alleviate the contradiction between SNIa BAO and CMB data.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P159

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