论文标题
使用Lyman-$α$ Forest进行预测宇宙加速度测量
Forecasting cosmic acceleration measurements using the Lyman-$α$ forest
论文作者
论文摘要
我们通过旨在限制宇宙扩展历史上的变化速率的观测值的端到端模拟,使用Lyman-$ lyman-$α$森林吸收线的红移漂移沿着视线朝向明亮的类星体。对于我们的模拟,我们采用从$ z> 3 $的凯克/雇用光谱中提取的lyman-$α$森林线,并将这些真实类星体光谱的结果与通过蒙特卡洛实现产生的模拟光谱进行比较。我们使用这些模拟的结果来评估专用观测站检测红移漂移的可能性,并量化这些观察值的望远镜和光谱仪的要求。相对于Liske等。 (2008年),当前工作中的两个主要改进是从最近的目录中包含了类星体,并考虑了专用的红移漂移实验的现实观察策略,该实验最大化$ \ dot {v}/σ_{\ dot {\ dot {v}}} $。我们发现,使用专用的设施和我们设计的观察计划,鉴于具有长期稳定性的长期稳定性,$ r = 50,000 $和25%的总系统效率,可以在15年内以3σ$的意义检测到红移漂移。为了实现这一意义,最佳目标数为四个类星体,根据$ \ dot {v}/σ_ {\ dot {v}} $观察加权时间和对象可见性。这种优化的策略导致望远镜直径下降9%,或者在所需的时间下减少6%,以达到与理想的S/N相同的S/N的均匀分配时间相同的S/N。
We present results from end-to-end simulations of observations designed to constrain the rate of change in the expansion history of the Universe using the redshift drift of the Lyman-$α$ forest absorption lines along the lines-of-sight toward bright quasars. For our simulations we take Lyman-$α$ forest lines extracted from Keck/HIRES spectra of bright quasars at $z>3$, and compare the results from these real quasar spectra with mock spectra generated via Monte Carlo realizations. We use the results of these simulations to assess the potential for a dedicated observatory to detect redshift drift, and quantify the telescope and spectrograph requirements for these observations. Relative to Liske et al. (2008), two main refinements in the current work are inclusion of quasars from more recent catalogs and consideration of a realistic observing strategy for a dedicated redshift drift experiment that maximizes $\dot{v}/σ_{\dot{v}}$. We find that using a dedicated facility and our designed observing plan, the redshift drift can be detected at $3σ$ significance in 15 years with a 25m telescope, given a spectrograph with long term stability with $R=50,000$ and 25% total system efficiency. To achieve this significance, the optimal number of targets is four quasars, with observing time weighted based upon $\dot{v}/σ_{\dot{v}}$ and object visibility. This optimized strategy leads to a 9% decrease in the telescope diameter or a 6% decrease in the required time to achieve the same S/N as for the idealized case of uniformly distributing time to the same quasars.