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arXiv 1503.01122astro-ph.CO
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关于光度距离和加速历元

On the luminosity distance and the epoch of acceleration

Will Sutherland, Paul Rothnie

备注：
Latex, 13 pages, 7 figures. Accepted by MNRAS. For the busy reader, Figs 4 and 6 are the main results
发表信息：
MNRAS (2015), 446, 3863
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摘要：

基于广义相对论（GR）和暗能量的标准宇宙学模型预测，宇宙在中等红移$z_{acc} \sim 0.7$处经历了从减速膨胀到加速膨胀的转变。显然，以一种与模型无关的方式直接测量这种转变是非常有趣的，而不需要假设GR是正确的引力理论。我们探讨在何种程度上超新星（SN）的光度距离测量提供了这样一个转变的证据：我们表明，与直觉相反，著名的“营业额”在SN距离残差$Δμ$相对于一个空的（米尔恩）模型不给这样一个转变的红移范围内跨越SN数据的有力证据。在该图中观察到的周转主要是由于米尔恩模型中的负曲率，{ \em not}是$Λ$ CDM和相关模型预测的减速。我们表明，有几个优点，在绘制距离残差对一个平面，非加速模型$(w = -1/3)$，并重新映射的$z-$轴到$u = \ln(1+z)$，我们概述了一些有用的和直观的属性，这个演示文稿。我们的结论是，有显着的互补性之间的SNe和重子声学振荡（BAO）：SNe提供高精度在低红移，并提供良好的约束净{ \em量}的加速度，因为$z \sim 0.7$，但在约束$z_{acc}$弱;而径向BAO测量可能是优越的直接约束$z_{acc}$。

英文摘要：

Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift $z_{acc} \sim 0.7$. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known "turnover" in the SN distance residuals $Δμ$ relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, {\em not} the deceleration predicted by $Λ$CDM and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model $(w = -1/3)$, and also remapping the $z-$axis to $u = \ln(1+z)$; we outline a number of useful and intuitive properties of this presentation. We conclude that there are significant complementarities between SNe and baryon acoustic oscillations (BAOs): SNe offer high precision at low redshifts and give good constraints on the net {\em amount} of acceleration since $z \sim 0.7$, but are weak at constraining $z_{acc}$; while radial BAO measurements are probably superior for placing direct constraints on $z_{acc}$.

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