New cosmology measurements with voids in next-generation galaxy surveys

1998年，天文学家有了一个惊人的发现：宇宙正在加速膨胀。这一结果导致了宇宙学的革命，并在我们的宇宙模型中引入了神秘的“暗能量”。对这种暗能量的理论理解仍然是最大的开放问题，不仅在宇宙学中，而且可能在所有物理学中。要解释暗能量，要么需要对真空能量的量子场论有新的理解，要么需要发现一个新的基本场，要么需要在非常大的尺度上对引力理论进行修正，正确的理论方法必须从观察中得到指导。新一代的星系巡天-- DESI、欧几里得和LSST --将从2020年开始上线，绘制数百万个星系在太空中的三维分布图。这些调查将提供一个前所未有的数据集来测量膨胀率，能够在我们对暗能量的认识中提供一个数量级的改进，并在宇宙学尺度上测试爱因斯坦的广义相对论。同样的数据也可以用来测量中微子的质量，比在地球上的实验室实验更好，以确定空间的曲率，甚至衡量宇宙的总质量。对我来说，这使它成为当代宇宙学中最令人兴奋的领域，但收集如此大量的数据既昂贵又耗时，必须尽可能有效地处理这些数据，以提取最大的信息。我已经开发出一种新的方法来测量宇宙学的数量从星系分布的基础上的大空区，或空洞，它们之间的属性。我领导了一项使用这种方法对当前数据的分析，证明它导致了任何现有星系调查中最精确的宇宙学测量。仅使用传统方法获得的信息相当于观测星系数量的四倍，而不需要额外的成本或观测时间。这些改进的测量已经大大降低了暗能量特性的不确定性，包括与其他类型的数据（如Ia型超新星和弱透镜）相结合时。当应用于第四阶段数据时，好处会更大。我将通过将这种新技术应用于分别于2020年和2022年开始运行的DESI和欧几里得光谱调查的数据来领导宇宙学测量。这将增加它们的信息含量，并提供宇宙学测量的黄金标准。我还将继续以其他方式使用宇宙空洞开发其他新的分析，应用于测光调查和LSST实验的数据，预计也将于2020年开始，这些项目将大大提高我们对暗能量的认识，中微子质量，哈勃常数和引力的替代理论在本奖学金的5年期间。

In 1998, astronomers made the surprising discovery that the expansion of the universe is accelerating. This result led to a revolution in cosmology and the introduction of a mysterious 'dark energy' in our model of the universe. A theoretical understanding of this dark energy remains the biggest open problem not just in cosmology, but perhaps in all of physics. The explanation for dark energy will require either a new understanding of the quantum field theory of vacuum energy, the discovery of a new fundamental field, or a modification of the theory of gravity on very large scales.Guidance as to the correct theoretical approach must be taken from observation. A new generation of galaxy surveys - DESI, Euclid and LSST - will start to come online from 2020 onwards, mapping the 3D distribution of millions of galaxies in space. These surveys will provide an unprecedented dataset with which to measure the expansion rate, capable of providing an order of magnitude improvement in our knowledge of dark energy as well testing Einstein's General Relativity on cosmological scales. The same data can also be used to measure the mass of neutrinos better than can be done in laboratory experiments on earth, to determine the curvature of space, and even to weigh the total mass of the Universe. To me, this makes it the most exciting field of contemporary cosmology.But collecting this vast amount of data is expensive and time-consuming, and it is imperative to process it as efficiently as possible to extract the maximum information. I have developed a new method for measuring cosmological quantities from the galaxy distribution that is based on the properties of the large empty regions, or voids, between them. I led an analysis of current data using this method, demonstrating that it leads to the most precise cosmological measurements from any existing galaxy survey. The information gain over the use of conventional methods alone is equivalent to quadrupling the number of galaxies observed, all while requiring no additional cost or observational time. These improved measurements already greatly reduce the uncertainty in dark energy properties, including when combined with other types of data such as Type Ia supernovae and weak lensing. When applied to Stage-IV data the benefits will be even greater. I will lead cosmological measurements by applying this new technique to data from the DESI and Euclid spectroscopic surveys that are starting operations in 2020 and 2022 respectively. This will increase their information content and provide the gold standard of cosmological measurements. I will also continue to develop additional new analyses using cosmic voids in other ways, for application to photometric surveys and data from the LSST experiment, which is also expected to start in 2020.Together, these projects will dramatically improve our knowledge of dark energy, neutrino masses, the Hubble constant and alternative theories of gravity over the 5-year duration of this Fellowship.