哈勃参量限制宇宙的backreaction效应

Constraining backreaction effects with observational Hubble parameter data

主要研究不均匀宇宙下的平均宇宙模型对宇宙加速膨胀的解释.首先,通过对该尘埃宇宙模型下的backreaction效应和Larena等提出的模板度规结合,得出了如下结论:FLRW度规对早期宇宙的演化能进行准确描述,但到晚期大约aD>0.1之后与backreaction模型区别明显.其次,选择通过有效哈勃参量来限制宇宙学参量.由于不能得到准确的尺度因子和红移关系,于是近似选择FLRW度规代替模板度规进行限制.限制结果发现Ωm=0.25+0.02-0.02(1σstat),与其他观测如超新星遗迹探测(SNLS)和Ⅰa型超新星等符合的很好.最后,通过限制结果的最佳拟合值对此模型下的宇宙学参量进行了分析,表明宇宙的backreaction效应可以很好解释宇宙加速膨胀,因此值得对此模型进行进一步的研究.

Interpretation of accelerated expansion of the universe within the framework of averaged inhomogeneous cosmology model is studied in the present work.Combining backreaction effects of dust cosmology model with template metric proposed by Larena et al.,it is concluded that FLRW metric can accurately describe evolution of the early universe.But after red-shift of up to aD0.1,difference between FLRW metric and backreaction model becomes apparent.The cosmological parameters are then constrained with the effective Hubble parameter.Since the exact relation between red-shifts and scale factor is not obtained,one can approximately elect FLRW metric to replace template metric to constrain them.The constraint value Ω_m= 0.25_（-0.02）^（＋0.02）（1σstat）fits the results of other cosmological models.Cosmological parameters are analyzed using best-fit values.It is found that backreaction effects of the universe can satisfactorily interpret accelerated expansion,so this model is worthwhile for further exploration.