“低頻射電天空輻射高仿真模擬與前景信號三窄頻段二項式擬合分離”科技報告
2017-03-13 03:36:47秦波
科技創新導報 2016年24期
秦波
摘 要：宇宙再電離觀測面臨的最大挑戰是21 cm信號極為微弱（～10mK）。第一代恒星（6 關鍵詞：數值模擬 射電觀測 宇宙再電離 信號處理 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
