Arizona State University, School of Earth and Space Exploration, Tempe, Arizona 85287, USA.
Nature. 2010 Dec 9;468(7325):796-8. doi: 10.1038/nature09601.
Observations of the 21-centimetre line of atomic hydrogen in the early Universe directly probe the history of the reionization of the gas between galaxies. The observations are challenging, though, because of the low expected signal strength (∼10 mK), and contamination by strong (>100 K) foreground synchrotron emission in the Milky Way and extragalactic continuum sources. If reionization happened rapidly, there should be a characteristic signature visible against the smooth foreground in an all-sky spectrum. Here we report an all-sky spectrum between 100 and 200 MHz, corresponding to the redshift range 6 < z < 13 for the 21-centimetre line. The data exclude a rapid reionization timescale of Δz < 0.06 at the 95% confidence level.
对早期宇宙中 21 厘米原子氢谱线的观测直接探测了星系间气体再电离的历史。然而，由于预期信号强度较低（约 10mK），以及银河系和河外连续源中的强（>100K）前景同步加速器发射的污染，观测具有挑战性。如果再电离发生得很快，那么在整个天空的光谱中，应该可以看到一个与平滑前景相对应的特征信号。在这里，我们报告了一个在 100 到 200MHz 之间的整个天空的光谱，对应于 21 厘米谱线的红移范围 6<z<13。数据在 95%置信水平下排除了 Δz<0.06 的快速再电离时标。
