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arXiv 1709.07258astro-ph.CO
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宇宙曲率和不透明度的模型无关约束

Model-independent Constraints on Cosmic Curvature and Opacity

Guo-Jian Wang, Jun-Jie Wei, Zheng-Xiang Li, Jun-Qing Xia, Zong-Hong Zhu

摘要:

在本文中,我们提出了一个独立于模型的方法来估计宇宙的空间曲率和宇宙的不透明度与膨胀率测量,$H(z)$,和Ia型超新星(SNe Ia)。一方面,利用非参数平滑方法高斯过程,我们重建了一个函数$H(z)$从不透明的膨胀率测量。然后,我们积分的$H(z)$获得距离模$μ_{\rm H}$,这是依赖于宇宙曲率。另一方面,Ia型超新星的距离可以通过光度观测来确定,因此与不透明度有关。在我们的分析中,面对距离模量$μ_{\rm H}$与那些从超新星Ia,我们实现了空间曲率和宇宙不透明度的估计,没有任何假设的宇宙学模型。在这里,应该注意的是,光变曲线拟合参数,占的距离估计的超新星Ia,确定在一个整体的拟合与宇宙的不透明度和空间曲率,以摆脱这些参数对宇宙学的依赖。此外,我们还调查是否包括不同的先验本膨胀率($H_0$:全球估计,$67.74\pm 0.46~\rm km~ s^{-1} ~Mpc^{-1}$,和本地测量,$73.24\pm 1.74~\rm km~ s^{-1} ~Mpc^{-1}$)施加影响重建$H(z)$和以下的空间曲率和宇宙不透明度的估计。结果表明,在一般情况下,一个空间平坦和透明的宇宙是首选的观测。此外,它表明,$H_0$的先验很重要。最后,我们发现在曲率和不透明度之间存在着很强的简并。

英文摘要:

In this paper, we propose to estimate the spatial curvature of the universe and the cosmic opacity in a model-independent way with expansion rate measurements, $H(z)$, and type Ia supernova (SNe Ia). On the one hand, using a nonparametric smoothing method Gaussian process, we reconstruct a function $H(z)$ from opacity-free expansion rate measurements. Then, we integrate the $H(z)$ to obtain distance modulus $μ_{\rm H}$, which is dependent on the cosmic curvature. On the other hand, distances of SNe Ia can be determined by their photometric observations and thus are opacity-dependent. In our analysis, by confronting distance moduli $μ_{\rm H}$ with those obtained from SNe Ia, we achieve estimations for both the spatial curvature and the cosmic opacity without any assumptions for the cosmological model. Here, it should be noted that light curve fitting parameters, accounting for the distance estimation of SNe Ia, are determined in a global fit together with the cosmic opacity and spatial curvature to get rid of the dependence of these parameters on cosmology. In addition, we also investigate whether the inclusion of different priors for the present expansion rate ($H_0$: global estimation, $67.74\pm 0.46~\rm km~ s^{-1} ~Mpc^{-1}$, and local measurement, $73.24\pm 1.74~\rm km~ s^{-1} ~Mpc^{-1}$) exert influence on the reconstructed $H(z)$ and the following estimations of the spatial curvature and cosmic opacity. Results show that, in general, a spatially flat and transparent universe is preferred by the observations. Moreover, it is suggested that priors for $H_0$ matter a lot. Finally, we find that there is a strong degeneracy between the curvature and the opacity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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