【作者】 杨荣佳；

【导师】 张双南；

【作者基本信息】 清华大学 ， 天体物理， 2008， 博士

【摘要】 在ACDM模型的年龄问题的研究中,为了避免Ω_m和H₀的值的选择依赖,我们将它们当作参数,在数据拟合中求得其最佳拟合值,从而考察ACDM模型是否满足古老星体的年龄限制。我们的研究表明,拟合182个SNIa数据、CMB和BAO观测和9个哈勃数据H（z）,宇宙现在的年龄满足球状星团的年龄（14Gyr）的限制,但是在很高置信区域里不能满足红移为z=3.91,年龄为2-3 Gyr的APM08279+5255的年龄限制。在纯动能k-essence理论研究中,我们得到一个形式简洁的理论限制。利用这个理论限制,我们发现,类phantom广义快子场不会导致未来大撕裂奇点,却会在过去导致奇点,除非它像宙常数那样演化。我们也利用纯动能k-essence的理论限制详细研究了类Chaplygin广义快子场模型,并利用182个SNIa数据和两个CMB观测参数R和l_a对模型参数进行限制,得到其最佳拟合值,进而研究了场的演化和能量密度的线性微扰。我们的结果表明:类Chaplygin广义快子场作为暗能量时,宇宙膨胀从减速过渡到加速时的红移为z_q=0～0.47-0.51;而对于类Chaplygin广义快子场作为暗能量和暗物质统一模型,z_q=0～0.49-0.68。我们首次运用9个H（z）数据无参数拟合和模型比较统计学,发现类Chaplygin广义快子场暗能量模型比ACDM模型与数据拟合要好,而后者比类Chaplygin广义快子场暗能量和暗物质统一模型与数据拟合要好。在广义测不准原理的基础上,我们推广了Salecker-Wigner不等式,并由此得到修正的黑洞寿命及黑洞信息的比特总量和以普朗克尺度为单位的黑洞事件视界的联系。同时,我们也考察了由Salecker-Wigner不等式可能得到的时空不等式,及可能建立的暗能量模型。更多还原

【Abstract】 With a 2-3 Gyr-old quasar APM08279+5255 at z=3.91,the age problem in the ACDM model is reexamined in a consistent way free of any systematic errors in measured values ofΩ_m and H₀.TheΛCDM model accommodates the total age（14 Gyr） of the Universe estimated from old globular clusters,but cannot accommodate this old quasar APM08279+5255 at high confidence level constrained from SNIa,CMB, BAO and H（z） observations.Studying the purely kinetic k-essence models in which the Lagrangian contains only a kinetic factor and does not depend explicitly on the field itself,we obtain a theoretical constraint.Under this theoretical constraint,we discuss the phantom-like generalized tachyon field,and find that this kind of generalized tachyon field will not result in a big rip,but will be singular in the past,unless it behaves like the cosmological constant.We consider constraints on Chaplygin-like generalized tachyon field models from latest observational data（including 182 gold SNIa data,the shift parameter,and the acoustic scale）.We obtain the best-fit values of the parameters and study the evolution of the field and the linear growth of field density fluctuations.By applying model-comparison statistics and test with independent H（z） data,we find the Chaplygin-like generalized tachyon field dark energy scenario is favored over theΛCDM model,and theΛCDM model is favored over the Chaplygin-like generalized tachyon field unified dark matter by the combined data.Based on the generalized uncertainty principle,Salecker-Wigner inequalities are generalized.When applied to black holes,they give a modified black hole lifetime and the relation between the entropy and the horizon of the black hole.We also discussed the spacetime uncertainty resulted from Salecker-Wigner inequalities.更多还原