摘要
自宇宙大爆炸结束,中性氢广泛分布于宇宙,为研究从宇宙黑暗时代、宇宙黎明与再电离时期,直到再电离之后的宇宙历史、精密测量物质分布提供了重要探针.但是迄今为止,由于灵敏度的限制,中性氢观测还主要局限于近邻宇宙.要进行更高红移的观测,必须在比其强几个数量级的前景中将21 cm信号提取出来,这对观测设备的设计和数据处理分析都提出了极高的要求.近年来,国际上出现了很多针对21 cm的观测实验,21 cm宇宙学正处在突破的前夜.我国也开展了21 cm宇宙学的探索性实验.本文介绍了暗能量射电探测关键技术实验(天籁实验阵列)和绕月超长波天文观测阵列(鸿蒙实验)的基本情况和研究进展.天籁实验阵列位于新疆巴里坤县红柳峡观测站,是用于试验中红移的大尺度结构21 cm强度映射的关键技术.鸿蒙实验则拟发射一个线形编队的卫星阵列,环绕月球飞行,进行全天频谱和干涉成像观测.这将打开一个新的观测窗口,并探索宇宙黑暗时代和宇宙黎明.
Since the end of the Big Bang,neutral hydrogen has been widely distributed in the universe,providing an important probe for studying the history of the universe from the dark age of the universe to cosmic dawn and reionization epoch,and then down to the post-reionization universe,and for accurately measuring the distribution of matter.But so far,due to the limitation of sensitivity,the observation of neutral hydrogen is mainly limited to the neighboring galaxies.To perform higher redshift observations,it is necessary to extract the 21 cm signal from foregrounds which are several orders of magnitude stronger.This places extremely high requirements on the design of observing instrument and data processing and analysis methods.In recent years,many 21 cm experiments have been built or being planned around the world,and21 cm cosmology is on the eve of a breakthrough.China has also carried out exploratory experiments on 21 cm cosmology.This article presents the basic design and research progress of two such experiments:The key technology experiment of dark energy radio detection(Tianlai Experimental Array),and the Discovering Sky at the Longest wavelength(DSL)experiment,a lunar orbit radio astronomical observation array.The Tianlai Experimental Array is located at the Hongliuxia Observatory in Balikun County,Xinjiang,and it was completed in 2016.It includes a cylindrical antenna array and a dish antenna array for mid-redshift 21 cm intensity mapping of large-scale structures.At present,we have conducted a preliminary analysis of the observation data and verified the calibration method and the system performance.In technology development,we are currently conducting research on the calibration of antennas with UAV;and on the science side,we will continue to improve the data processing methods,focusing on surveys of the north celestial pole region,and plan to conduct Fast Radio Burst(FRB)searches.The DSL experiment intends to launch a linear formation of satellites to fly around the moon as an array,to conduct global spectrum measurement and interferometry imaging observations.This will open up a new observation window in the electromagnetic spectrum,that is,the frequency band below 30 MHz,which is difficult to observe from the ground due to the Earth ionosphere absorption,refraction and radio frequency interferences(RFI),with great potential for new discoveries of the unknown.It will also accurately measure the global spectrum under more ideal conditions,exploring the dark ages and cosmic dawn.
作者
陈学雷
Xuelei Chen(National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China;School of Astronomy and Space Science,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2021年第11期1385-1398,共14页
Chinese Science Bulletin
基金
政府间国际科技创新合作重点专项(2018YFE0120800)
国家自然科学基金(11633004,U1631118,U1501501,11473044,11773031)
中国科学院前沿科学重点项目(QYZDJ-SSW-SLH017)
中国科学院修缮购置项目
中国科学院空间科学战略先导科技专项(XDA15020200)
中国科学院科研仪器重点项目(ZDKYYQ20200008)
国家天文台预研项目
中以合作项目(20171352322)资助。
