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arXiv 0908.1438astro-ph.CO
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Cardassian模型的最新观测约束

Latest Observational Constraints on Cardassian Models

Tai-Shan Wang, Puxun Wu

摘要:

利用最新的397颗Ia型超新星(SNe Ia)资料、Sloan数字巡天(SDSS)的重子声振荡峰的大小、Wilkinson微波各向异性探测器(WMAP)5年观测的宇宙微波背景辐射(CMB)第一声峰的位置,星系团中的x射线气体质量分数,以及观测的H(z)数据。在这些组合数据集的原始Cardassian模型中,我们在$1 σ$置信水平下发现了$Ω_{m0}=0.271^{+0.014}_{-0.014}, n=0.035^{+0.049}_{-0.049}$。而在修正的多方Cardassian模型中,我们发现$Ω_{m0}=0.271^{+0.014}_{-0.015}$、$n=-0.091^{+0.331}_{-1.908}$和$β=0.824^{+0.750}_{-0.622}$都在$1σ$置信水平之内。根据这些观测,宇宙的加速对于原始的卡达西模型是从$z_T=0.55^{+0.05}_{-0.05} (1σ)$开始的,对于修正的多方卡达西模型是从$z_T=0.58^{+0.12}_{-0.12} (1σ)$开始的。本文还研究了修正的多方Cardassian模型的有效状态方程$w_{eff}$的演化,结果表明演化的精髓暗能量模型是有利的。

英文摘要:

Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the latest derived 397 Type Ia supernova (SNe Ia) data, the size of baryonic acoustic oscillation peak from the Sloan Digital Sky Survey (SDSS), the position of first acoustic peak of the Cosmic Microwave Background radiation (CMB) from the five years Wilkinson Microwave Anisotropy Probe (WMAP), the x-ray gas mass fractions in clusters of galaxies, and the observational H(z) data. In the original Cardassian model with these combined data set, we find $Ω_{m0}=0.271^{+0.014}_{-0.014}, n=0.035^{+0.049}_{-0.049}$ at $1 σ$ confidence level. And in the modified polytropic Cardassian model, we find that $Ω_{m0}=0.271^{+0.014}_{-0.015}$, $n=-0.091^{+0.331}_{-1.908}$ and $β=0.824^{+0.750}_{-0.622}$ within $1σ$ confidence level. According to these observations, the acceleration of the universe begins at $z_T=0.55^{+0.05}_{-0.05} (1σ)$ for the original Cardassian model, and at $z_T=0.58^{+0.12}_{-0.12} (1σ)$ for the modified polytropic Cardassian model. Evolution of the effective equation of state $w_{eff}$ for the modified polytropic Cardassian model is also examined here and results show that an evolutionary quintessence dark energy model is favored.

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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