暗能量EoS中的振荡：新的MCMC课程
Oscillations in the dark energy EoS: new MCMC lessons
摘要：
我们研究了使用不同的宇宙学数据集探测暗能量状态方程振荡模式的可能性。我们遵循现象学的方法和研究三种不同的振荡模型的EoS，其中一个周期性和其他两个阻尼（这里提出的第一次）。所有模型的特征在于振幅值，振荡的中心和频率。与文献中以前的工作相比，我们没有将频率的值固定为与所选数据集的时间扩展相关的基准值，而是考虑一组离散值，以避免任意性并尝试检测EoS中的任何可能的时间段。我们测试的模型，使用最近收集的SNeIa，直接哈勃数据和伽马射线暴数据。主要结果如下：I.即使对幅度的约束不是太强，我们也检测到它相对于频率的趋势，即，对于较高频率，幅度减小（甚至为负）; II.振荡中心（对应于EoS参数的当前值）受到很好的约束，在$1σ$水平排除了幻像行为，并出现与振幅一致的趋势; III.频率是很难约束的，显示出类似的统计有效性的所有值的离散集选择，但最适合的所有考虑的情况是与一个周期，这是在红移范围内描绘我们的宇宙学数据。“最好的”振荡模型进行了比较$Λ$ CDM使用尺寸一致的贝叶斯方法为基础的信息标准和得出的结论是不存在的显着证据对暗能量振荡。
英文摘要：
We study the possibility of detecting oscillating patterns in the equation of state (EoS) of the dark energy using different cosmological datasets. We follow a phenomenological approach and study three different oscillating models for the EoS, one of them periodic and the other two damped (proposed here for the first time). All the models are characterised by the amplitude value, the centre and the frequency of oscillations. In contrast to previous works in the literature, we do not fix the value of the frequency to a fiducial value related to the time extension of chosen datasets, but consider a discrete set of values, so to avoid arbitrariness and try and detect any possible time period in the EoS. We test the models using a recent collection of SNeIa, direct Hubble data and Gamma Ray Bursts data. Main results are: I. even if constraints on the amplitude are not too strong, we detect a trend of it versus the frequency, i.e. decreasing (and even negatives) amplitudes for higher frequencies; II. the centre of oscillation (which corresponds to the present value of the EoS parameter) is very well constrained, phantom behaviour is excluded at $1σ$ level and trend which is in agreement with the one for the amplitude appears; III. the frequency is hard to constrain, showing similar statistical validity for all the values of the discrete set chosen, but the best fit of all the scenarios considered is associated with a period which is in the redshift range depicted by our cosmological data. The "best" oscillating models are compared with $Λ$CDM using dimensionally consistent a Bayesian approach based information criterion and the conclusion reached is the non existence of significant evidence against dark energy oscillations.
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