宇宙黎明和再电离时期探测进展

Progress on the Exploration of the Cosmic Dawn and the Epoch of Reionization

宇宙黎明和再电离信号探测是目前运行以及即将建成的低频射电阵列(如平方公里阵列square kilometer array, SKA)的首要科学目标之一。红移z=6~27时期的HI超精细能级跃迁产生的21 cm辐射是进行宇宙黎明和再电离时期探测的最直接而有效的工具,通过探测HI的21 cm信号可以描绘出宇宙第一代发光天体的产生和形成过程,从而研究宇宙从黑暗走向光明的历史。主要介绍近年来宇宙黎明和再电离探测方向的相关研究进展,讨论了在宇宙黎明和再电离探测时期探测中关于前景去除、数据处理方法等相关问题,以及低频射电望远镜在全天总功率测量、功率谱测量方面的研究进展。

The cosmic dawn(CD)and epoch of reionization(EoR)are two of the most important missing pictures in the history of the Universe.The first luminous objects were formed during the CD/EoR period and thus marked the end of the dark ages.Detecting the redshifted 21cm hyperfine transition line of neutral hydrogen is regarded as the most promising and effective one to probe the CD/EoR.It includes three aspects:the total power measurement of the CD/EoR,the statistical measurement of the CD/EoR signal and perform imaging observations on the reionization area directly.Recently,a lot of related works have been done on both theories and observations,including i)theories and numerical simulations on the IGM evolution history during EoR;ii)data processing methods including radio frequency interference(RFI)removal,data calibration,techniques of foregrounds removal,etc.It makes great progress on the global detections and statistic measurements of the CD/EoR signals.As the largest radio telescope ever built,the Square Kilometer Array(SKA)will enable us a better understanding of the history and morphology of the CD/EoR.This work will provide a brief overview of the related research progress of CD/EoR detection in recent years.