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arXiv 0905.1234astro-ph.CO
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最新Ia超新星、BAO和SGL的暗能量和哈勃常数

Dark Energy and Hubble Constant From the Latest SNe Ia, BAO and SGL

Qing-Jun Zhang, Yue-Liang Wu

摘要:

基于Hessel等(2009)提供的最新MLCS 17 SNe Ia数据,结合重子声振荡(BAO)和强引力透镜(SGL),研究了平坦宇宙中常数$w$和时变$w(z)=w_0+w_az/(1+z)$的暗能量状态方程参数及其与物质密度$Ω_M$和哈勃常数$h$的相关性.由SNe数据得到的约束条件为:(a)最佳拟合结果为$(Ω_M, w, h)=(0.358, -1.09, 0.647)$,而$Ω_M$和$w$均对哈勃常数与先验输入$\tilde{h}=0.65$的差值$Δh =h-\tilde{h}$非常敏感;(b)参数的似然度为:$w = -0.88^{+0.31}_{-0.39}$和$Ω_M=0.36^{+0.09}_{-0.15}$,与95% C. L.下的$Λ\rm CDM$一致; (c)在对其他参数进行边缘化之后,发现时变情况下的两个参数是$(w_0, w_a)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34})$;(d)在常数$w$和$Ω_M$之间存在明显的简并性,这降低了SNe Ia约束它们两者的能力;(e)参数$w_a$的似然性具有高的非高斯分布;(f)对$Ω_M$的额外限制是必要的,以改善SNe Ia数据对($w_0$,$w_a$)的约束。通过对Ia型超新星和BAO的联合分析,打破了$w$和$Ω_M$之间的简并性,并给出了一个严格的似然约束:$w = -0.88^{+0.07}_{-0.09}$和$Ω_M=0.29^{+0.02}_{-0.03}$ .对于随时间变化的$w(z)$,它导致有趣的最大似然$w_0 = -0.94$和$w_a = 0$。当边缘化参数$Ω_M$和$h$时,发现拟合结果是$(w_0, w_a)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96})$。

英文摘要:

Based on the latest MLCS17 SNe Ia data provided by Hicken et al. (2009), together with the Baryon Acoustic Oscillation (BAO) and strong gravitational lenses (SGL), we investigate the dark energy equation-of-state parameter for both constant $w$ and time-varying $w(z)=w_0+w_az/(1+z)$ in the flat universe, and its correlation with the matter density $Ω_M$ and Hubble constant $h$. The constraints from SNe data alone arrive at: (a) the best-fit results are $(Ω_M, w, h)=(0.358, -1.09, 0.647)$, while both $Ω_M$ and $w$ are very sensitive to the difference $Δh =h-\tilde{h}$ of the Hubble constant deviating to the prior input $\tilde{h}=0.65$; (b) the likelihoods of parameters are found to be: $w = -0.88^{+0.31}_{-0.39}$ and $Ω_M=0.36^{+0.09}_{-0.15}$, which is consistent with the $Λ\rm CDM$ at 95% C.L.; (c) the two parameters in the time-varying case are found to be $(w_0, w_a)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34})$ after marginalizing other parameters; (d) there is a clear degeneracy between constant $w$ and $Ω_M$, which depresses the power of SNe Ia to constrain both of them; (e) the likelihood of parameter $w_a$ has a high non-Gaussian distribution; (f) an extra restriction on $Ω_M$ is necessary to improve the constraint of the SNe Ia data on ($w_0$, $w_a$). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between $w$ and $Ω_M$, and it provides a stringent constrain with the likelihoods: $w = -0.88^{+0.07}_{-0.09}$ and $Ω_M=0.29^{+0.02}_{-0.03}$. For the time-varying $w(z)$, it leads to the interesting maximum likelihoods $w_0 = -0.94$ and $w_a = 0$. When marginalizing the parameters $Ω_M$ and $h$, the fitting results are found to be $(w_0, w_a)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96})$.

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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