基于红移畸变测量宇宙结构增长率的进展

Research Process on Measuring the Cosmic Growth Rate by the Redshift-Space Distortions

星系红移巡天的一个主要目标是依据光谱红移测距,详细刻画宇宙中星系的三维空间分布。由于星系本动速度的存在,红移空间的星系分布存在着严重畸变,在大小尺度上有着不同模式的各向同性偏离。通过对红移畸变的观测研究,人们可从中获取速度场的信息,因此,红移畸变已成为暗能量探测的重要探针之一,为检验宇宙学尺度上的引力模型提供帮助。当前星系红移巡天项目已经取得了非凡成功,为人们提供了详细的星系空间分布数据。人们据此测量了星系的相关函数和功率谱,提取了精确的红移畸变信号,并通过模型拟合限制出了一批不同红移处宇宙结构增长率的估值,为探索宇宙尺度的引力模式提供了数据支持。主要介绍红移畸变模型、星系红移巡天观测和宇宙结构增长率测量等研究进展。

One of the main goals of large redshift surveys is to provide a database for studying the three-dimensional distribution of galaxies as accurately as possible.However,a key problem of this endeavor is that redshifts of galaxies are not exact measures of distances because of the peculiar motions of galaxies.The spatial distribution and clustering in redshift space are thus distorted with respect to the real-space distribution and clustering.The twodimensional statistics,such as correlation function or power spectrum,appear elongated on small scales and squashed on large scales along line-of-sight,in contrast to the isotropic pattern in real space.On the other hand,the redshift-space distortions(RSD),one of the important tools in cosmology,can provide the information regarding the velocity field,probe the dark energy and test the gravity on cosmological scale.Current galaxy surveys have succeeded greatly in mapping the galaxy distribution at different redshift.More and more accurate RSD signals have been extracted from the correlation function or power spectrum of galaxies obtained in the survey.A series of estimations for the cosmic growth rate at different redshift have thus been constrained by the RSD models,and provide a big database for testing the gravity.In this paper,we review the RSD models,introduce some main galaxy redshift surveys finished in recent years,and summarize the procedures in measuring the growth rate based on these surveys.