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arXiv 1201.3499astro-ph.CO
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标量场幂律宇宙学的WMAP7约束

WMAP7 constraints on scalar-field power-law cosmology

Burin Gumjudpai, Chakkrit Kaeonikhom

备注：
This article has been withdrawn by the author due to new version submission with substantially change to the content. The new version appears on arXiv:1307.4552
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摘要：

本文研究了尺度因子为时间幂次的幂律宇宙学$a \propto t^{\a}$。考虑到具有正则标量场和尘埃占优的晚期宇宙，我们利用宇宙微波背景辐射（WMAP 7）、重子声振荡（BAO）和哈勃观测数据，求出了幂律的幂指数$\a$和其他宇宙学变量。发现功率$\a$是$0.99 \pm 0.02$（WMAP 7 +BAO+ $H_0$）和$0.99 \pm 0.04$（WMAP 7）。这些值并不排除在1 $σ$加速的可能性，因此一般来说，幂律宇宙学是可行的。在考虑正则标量场暗能量幂律展开的情况下，我们导出了标量场势、精确解、状态方程参数，并利用观测数据绘制了它们的演化曲线。我们确认，WMAP 7数据排除了包含动力学正则标量场的幂律宇宙学的可能性，因为它的状态方程参数的当前值与WMAP 7的结果不匹配，即使用WMAP 7的标量场幂律宇宙学给出了$w_{ϕ, 0} = -0.4493 \pm 0.0300 $，而使用WMAP 7的$w_ϕ$ CDM允许在$w_{ϕ, 0} = -0.69$处状态方程参数的最大值（+1 $σ$）。

英文摘要：

In this paper, power-law cosmology whose scale factor is a power of time, $a \propto t^{\a}$, is investigated. Considering late universe with canonical scalar field and dust domination, we use observational data from Cosmic Microwave Background (WMAP7), Baryon Acoustic Oscillations (BAO) and observational Hubble data to find power exponent $\a$ of the power-law and other cosmological variables. The power $\a$ is found to be $0.99 \pm 0.02$ (WMAP7+BAO+$H_0$) and $0.99 \pm 0.04$ (WMAP7). These values do not exclude possibility of acceleration at 1$σ$ hence giving viability to power-law cosmology in general. When considering scenario of canonical scalar field dark energy with power-law expansion, we derive scalar field potential, exact solution, equation of state parameter and plots their evolutions using observational data. We confirm that the scenario of power-law cosmology containing dynamical canonical scalar field is ruled out by WMAP7 data since its present value of equation of state parameter does not match the WMAP7 result, i.e. the scalar-field power-law cosmology using WMAP7 gives $w_{ϕ, 0} = -0.4493 \pm 0.0300 $ while the $w_ϕ$CDM with WMAP7 data allows a maximum (+1$σ$) value of the equation of state parameter at $w_{ϕ, 0} = -0.69$.

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