时间:2024-08-31
秦波
摘 要:宇宙再電离观测面临的最大挑战是21 cm信号极为微弱(~10mK)。第一代恒星(6 关键词:数值模拟 射电观测 宇宙再电离 信号处理 Report on “Exploring the Cosmic Reionization Epoch in Frequency Space: An Improved Approach to Remove the Foreground in 21cm Tomography” Qin Bo (National Astronomical Observatories,Chinese Academy of Sciences) Abstract:By adopting a complex foreground model, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency spac e in order to investigate whether they work satisfactorily by quantitatively evaluating the quality of restored 21 cm signals (both spectra and power spectra) in terms of sample statistics. We find that a significant part of the Mpc-scale components of the 21 cm signals (75% for & 6 h-1 Mpc scales and 34% for & 1 h-1 Mpc scales) is lost using the traditional separation algorithm, because it tends to be misidentified as part of the foreground when the single-narrow-segment separation approach is applied. The best restoration of the 21 cm signals and the tightest determination of the mean halo b and average ionization fraction xe can be obtained with the three-narrow-segment fitting technique as proposed in this report. Key Words:Numerical simulation; Radio observation; Reionization; Signal processing
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