论文标题
宇宙空隙作为宇宙实验室
Cosmic voids as cosmological laboratories
论文作者
论文摘要
宇宙空隙是有希望的宇宙实验室，用于研究黑暗能量现象和替代重力理论。鉴于新一代的Galaxy Spectroscic Surveys涵盖了前所未有的体积和红移范围，他们如今已受到特别关注。空隙研究中有两个主要的统计数据：（i）尺寸函数，表征了空隙的丰度，以及（ii）空隙 - 摩肌互相关函数，其中包含有关这些区域中密度和速度场的信息。但是，有必要完整描述几何（Alcock-Paczynski效应，AP）和动力学（Kaiser效应，RSD）扭曲的影响，以根据这些统计数据设计可靠的宇宙学测试。观察测量结果显示出明显的各向异性模式，如果未正确建模，则会导致各各向异性模式。本文通过基于动态和宇宙学基础提出一个理论和统计框架来解决这一问题，该框架能够描述所涉及的所有潜在效果：扩展效应（T-RSD），偏置效应（V-RSD），AP-VOLUME效应和椭圆度效应（E-RSD）。可以通过研究真实和红移空间之间空隙的映射来理解这些效果。通过这种方式，我们为上述统计数据做出适当的建模奠定了基础。此外，我们基于相关函数的两个垂直投影提出了一项新的宇宙学测试。该方法是不含基准化学的方法，这使我们能够有效地打破所涉及的宇宙学参数之间的任何可能的堕落性。此外，它使我们能够显着减少估计协方差所需的模拟目录的数量。
Cosmic voids are promising cosmological laboratories for studying the dark energy phenomenon and alternative gravity theories. They are receiving special attention nowadays in view of the new generation of galaxy spectroscopic surveys, which are covering an unprecedented volume and redshift range. There are two primary statistics in void studies: (i) the void size function, which characterises the abundance of voids, and (ii) the void-galaxy cross-correlation function, which contains information about the density and velocity fields in these regions. However, it is necessary a complete description of the effects of geometrical (Alcock-Paczynski effect, AP) and dynamical (Kaiser effect, RSD) distortions around voids in order to design reliable cosmological tests based on these statistics. Observational measurements show prominent anisotropic patterns that lead to biased cosmological constraints if they are not properly modelled. This thesis addresses this problematic by presenting a theoretical and statistical framework based on dynamical and cosmological foundations capable of describing all the underlying effects involved: the expansion effect (t-RSD), the off-centring effect (v-RSD), the AP-volume effect and the ellipticity effect (e-RSD). These effects can be understood by studying the mapping of voids between real and redshift space. In this way, we lay the foundations for a proper modelling of the aforementioned statistics. In addition, we present a new cosmological test based on two perpendicular projections of the correlation function. The method is fiducial-cosmology free, which allows us to effectively break any possible degeneracy between the cosmological parameters involved. Moreover, it allows us to significantly reduce the number of mock catalogues needed to estimate covariances.
