Parameters and pitfalls in dark energy models with time varying equation of state
Parameters and pitfalls in dark energy models with time varying equation of state
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发表时间：
2009-03
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通讯作者：
R. Biswas;B. Wandelt
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作者：
R. Biswas;B. Wandelt
CMB和LSS的几何总结是否足以估计宇宙学参数？我们对暗能量模型的选择如何影响标准宇宙学参数的当前约束？我们解决这些问题的背景下，广泛使用的CPL参数化的时变状态方程w在宇宙学允许空间曲率。我们研究的例子中允许在CPL参数化的相图不同的行为，并将这些影响的观测。我们检查参数约束在这样的宇宙学结合WMAP 5，SDSS，SNe，HST数据集通过比较功率谱。我们仔细量化这些约束的差异，通过使用相同的数据集的几何总结。我们发现，（a）使用摘要参数，而不是完整的数据集给出的参数约束是相似的，但有明显的差异，（B）由于退化，对标准参数的约束显着扩大相同的数据集。特别是，我们发现在CPL暗能量的背景下，（i）Harrison-Zeldovich光谱不能排除在我们目前的数据集的2sigma水平。以及（ii）SNe IA、HST和WMAP 5数据不足以约束空间曲率;我们还需要SDSS DR 4数据来实现这一点。
Are geometrical summaries of the CMB and LSS sufficient for estimating cosmological parameters? And how does our choice of a dark energy model impact the current constraints on standard cosmological parameters? We address these questions in the context of the widely used CPL parametrization of a time varying equation of state w in a cosmology allowing spatial curvature. We study examples of different behavior allowed in a CPL parametrization in a phase diagram, and relate these to effects on the observables. We examine parameter constraints in such a cosmology by combining WMAP5, SDSS, SNe, HST data sets by comparing the power spectra. We carefully quantify the differences of these constraints to those obtained by using geometrical summaries for the same data sets. We find that (a) using summary parameters instead of the full data sets give parameter constraints that are similar, but with discernible differences, (b) due to degeneracies, the constraints on the standard parameters broaden significantly for the same data sets. In particular, we find that in the context of CPL dark energy, (i) a Harrison-Zeldovich spectrum cannot be ruled out at $2\sigma$ levels with our current data sets. and (ii) the SNe IA, HST, and WMAP 5 data are not sufficient to constrain spatial curvature; we additionally require the SDSS DR4 data to achieve this.