A struggle to reionize the Universe?
成果类型：
Editorial Material
署名作者：
Scarlata, Claudia
署名单位：
University of Minnesota System; University of Minnesota Twin Cities
刊物名称：
SCIENCE
ISSN/ISSBN：
0036-9984
DOI：
10.1126/science.adp5153
发表日期：
2024-05-24
页码：
851-851
关键词：
摘要：
Reservoirs of neutral hydrogen may block ionizing radiation from escaping distant galaxies Hydrogen in the intergalactic medium, the diffuse gas that permeates the space between galaxies, exists today in an ionized state ( 1 ). Yet, this hasn't always been the case. Very early on, approximately 400,000 years after the Big Bang, the intergalactic medium was primarily neutral. The subsequent transition to an ionized universe, known as reionization, lasted about a billion years and remains poorly understood. Ionization occurs when hydrogen absorbs a photon from the far-ultraviolet (UV) region of the electromagnetic spectrum, which breaks the electron-nucleus bond. It is thought that the first stars and galaxies initiated this transformation. On page 890 of this issue, however, Heintz et al. ( 2 ) report three galaxies harboring substantial reservoirs of neutral hydrogen a few hundreds of millions of years after the Big Bang, a time when this transition is expected to occur. This challenges the role that early galaxies play in the reionization process.