Cosmic dynamics in the era of Extremely Large Telescopes
J. Liske, A. Grazian, E. Vanzella, M. Dessauges, M. Viel, L. Pasquini, M. Haehnelt, S. Cristiani, F. Pepe, G. Avila, P. Bonifacio, F. Bouchy, H. Dekker, B. Dela… 展开作者
J. Liske, A. Grazian, E. Vanzella, M. Dessauges, M. Viel, L. Pasquini, M. Haehnelt, S. Cristiani, F. Pepe, G. Avila, P. Bonifacio, F. Bouchy, H. Dekker, B. Delabre, S. D'Odorico, V. D'Odorico, S. Levshakov, C. Lovis, M. Mayor, P. Molaro, L. Moscardini, M. T. Murphy, D. Queloz, P. Shaver, S. Udry, T. Wiklind, S. Zucker
备注：
Accepted for publication in MNRAS, 27 pages, 19 figures
由于宇宙膨胀率的演变，所有宇宙学上遥远的源的红移预计将经历一个小的，系统的漂移作为时间的函数。对这种效应的测量将代表在其他方法无法达到的红移范围内直接和完全独立于模型的宇宙膨胀历史的确定。在这里，我们调查的影响，下一代极大望远镜的可行性检测和表征宇宙学红移漂移。我们认为红移范围2 < z < 5的莱曼α森林和高红移类星体光谱中的其他吸收线是最适合进行红移漂移实验的目标。假设光子噪声有限的意见，并使用广泛的蒙特卡罗模拟，我们确定的准确性，可以测量的红移漂移的信号-噪声和红移的函数从Ly α森林。基于这种关系，并使用已知的类星体的亮度和红移分布，我们发现，一个42米的望远镜是能够明确地检测到的红移漂移在一个为期约20年，使用4000小时的观测时间。这样的实验将为暗能量的存在提供独立的证据，而无需假设空间平坦，使用任何其他宇宙学约束或做出任何其他天体物理学假设。
英文摘要：
The redshifts of all cosmologically distant sources are expected to experience a small, systematic drift as a function of time due to the evolution of the Universe's expansion rate. A measurement of this effect would represent a direct and entirely model-independent determination of the expansion history of the Universe over a redshift range that is inaccessible to other methods. Here we investigate the impact of the next generation of Extremely Large Telescopes on the feasibility of detecting and characterising the cosmological redshift drift. We consider the Lyman alpha forest in the redshift range 2 < z < 5 and other absorption lines in the spectra of high redshift QSOs as the most suitable targets for a redshift drift experiment. Assuming photon-noise limited observations and using extensive Monte Carlo simulations we determine the accuracy to which the redshift drift can be measured from the Ly alpha forest as a function of signal-to-noise and redshift. Based on this relation and using the brightness and redshift distributions of known QSOs we find that a 42-m telescope is capable of unambiguously detecting the redshift drift over a period of ~20 yr using 4000 h of observing time. Such an experiment would provide independent evidence for the existence of dark energy without assuming spatial flatness, using any other cosmological constraints or making any other astrophysical assumption.
The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys
Kilodegree Extremely Little Telescope（KELT）是一个观测明亮恒星的行星凌日的项目。它由一个小口径、宽视场自动望远镜组成，位于亚利桑那州Sonoita附近的Winer天文台。该望远镜观测一组26 x 26度的视场，共覆盖北半球天空的25%，目标是8<V<10等的恒星，通过近距离的望远镜寻找凌日。本文介绍了系统的硬件和软件，并讨论了观测质量。我们表明，KELT是能够实现必要的光度精度，以检测行星凌日围绕太阳型主序星。
明亮恒星的凌日提供了一个独特的机会来研究太阳系外行星的详细性质，这些性质无法通过径向速度观测来确定。我们提出了一种技术，找到这样的系统使用全天空小孔径过境调查。寻找明亮恒星凌日的最佳望远镜设计是一个5厘米的“望远镜”，配备一个4k x 4k相机。我们目前正在建造这样一个系统，预计在运行一年后将探测到约10颗明亮的恒星凌日。
