A Comparison of cosmological models using recent supernova data
A Comparison of cosmological models using recent supernova data
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DOI：
10.1103/physrevd.70.043531
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发表时间：
2004-01
影响因子：
5
通讯作者：
S. Nesseris;L. Perivolaropoulos
中科院分区：
文献类型：
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作者：
S. Nesseris;L. Perivolaropoulos
我们使用Tonry等人最近发表的194个SNIA数据来研究宇宙的膨胀历史，直到红移$\mathm{z}=1.75$。和Barris等人。特别是，我们找到了几个宇宙学模型和$H(Z)$ansatze的最佳拟合形式，确定了它们参数的最佳拟合值，并根据每个$H(Z)$ansatz的递增值${\ensureath{\chi}_{\mathm{min}}^{2}$[${\ensureath{\chi}}^{2}$]对它们进行了排序。我们使用合理的先验条件将${\ensureath{\omega}}_{0m}$视为参数，并假定宇宙的几何形状是平坦的。关于能源条件的有效性，没有事先的假设。拟合的模型有14个，包括标准冷暗物质(SCDM)，具有宇宙学常数的冷暗物质(LCDM)，具有常态方程参数的暗能量w(Quessence)，$H(1+z)的三阶多项式，$Chaplygin气体，Cardassian模型，${w(Z)=w}_{0}{+w}_{1}z，${w(Z)=w}_{0}{+zw}_{1}/(1+z)，$H(Z)的振荡变换，$等。除SCDM外，所有这些模型都与当前数据一致。然而，它们之间的拟合质量差异很大，预测的最佳拟合形式$w(Z)$和$H(Z)$也是如此。在所考虑的数据一致性模型中，最差的拟合对应于最简单的模型lcdm$({\ensuremath{\chi}}_{\mathrm{min}}^{2}=198.7$，其值为${\ensureath{\\omega}}_{0m}=0.34)$而最佳拟合是通过三个参数振荡的$({\ensuremath{\chi}}_{\mathrm{min}}^{2}=193.8).$来实现的。大多数最佳拟合的ansatze具有一个状态方程参数$w(Z)$，该参数在对于$zl0.5$，$w(Z)G0$。这意味着暗能量的压强符号可能随着红移的增加而交替。振荡的$H(Z)$ansatz的拟合优度进一步支持了这种可能性。
We study the expansion history of the universe up to a redshift of $\mathrm{z}=1.75$ using the 194 recently published SnIa data by Tonry et al. and Barris et al. In particular we find the best fit forms of several cosmological models and $H(z)$ ansatze, determine the best fit values of their parameters and rank them according to increasing value of ${\ensuremath{\chi}}_{\mathrm{min}}^{2}$ [the minimum value of ${\ensuremath{\chi}}^{2}$ for each $H(z)$ ansatz]. We treat ${\ensuremath{\Omega}}_{0m}$ as a parameter using a reasonable prior and assume flat geometry of the universe. No prior assumptions are made about validity of energy conditions. The fitted models are fourteen and include standard cold dark matter (SCDM), cold dark matter with cosmological constant \ensuremath{\Lambda} (LCDM), dark energy with constant equation of state parameter w (quiessence), third order polynomial for $H(1+z),$ Chaplygin gas, Cardassian model, ${w(z)=w}_{0}{+w}_{1}z,$ ${w(z)=w}_{0}{+zw}_{1}/(1+z),$ an oscillating ansatz for $H(z),$ etc. All these models with the exception of SCDM are consistent with the present data. However, the quality of the fit differs significantly among them and so do the predicted forms of $w(z)$ and $H(z)$ at best fit. The worst fit among the data-consistent models considered corresponds to the simplest model LCDM $({\ensuremath{\chi}}_{\mathrm{min}}^{2}=198.7$ for ${\ensuremath{\Omega}}_{0m}=0.34)$ while the best fit is achieved by the three parameter oscillating ansatz $({\ensuremath{\chi}}_{\mathrm{min}}^{2}=193.8).$ Most of the best fit ansatze have an equation of state parameter $w(z)$ that varies between $w(z)\ensuremath{\simeq}\ensuremath{-}1$ for $zl0.5$ to $w(z)g0$ for $zg1.$ This implies that the sign of the pressure of the dark energy may be alternating as the redshift increases. The goodness of fit of the oscillating $H(z)$ ansatz lends further support to this possibility.