NAOC Open IR  > 射电天文研究部
Foreground removal of 21 cm fluctuation with multifrequency fitting
He, Li-Ping1,2
AbstractThe 21 centimeter (21 cm) line emission from neutral hydrogen in the inter-galactic medium (IGM) at high redshifts is strongly contaminated by foreground sources such as the diffuse Galactic synchrotron emission and free-free emission from the Galaxy, as well as emission from extragalactic radio sources, thus making its observation very complicated. However, the 21 cm signal can be recovered through its structure in frequency space, as the power spectrum of the foreground contamination is expected to be smooth over a wide band in frequency space while the 21 cm fluctuations vary significantly. We use a simple polynomial fitting to reconstruct the 21 cm signal around four frequencies 50, 100, 150 and 200 MHz with an especially small channel width of 20 kHz. Our calculations show that this multifrequency fitting approach can effectively recover the 21 cm signal in the frequency range 100 similar to 200 MHz. However, this method doesn't work well around 50 MHz because of the low intensity of the 21 cm signal at this frequency. We also show that the fluctuation of detector noise can be suppressed to a very low level by taking long integration times, which means that we can reach a sensitivity of approximate to 10 mK at 150 MHz with 40 antennas in 120 hours of observations.
KeywordMethods: Data Analysis Cosmology: Theory Observations Diffuse Radiation
Indexed BySCI
WOS IDWOS:000267180100004
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Document Type期刊论文
Affiliation1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China
2.Chinese Acad Sci, Grad Univ, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
He, Li-Ping. Foreground removal of 21 cm fluctuation with multifrequency fitting[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2009,9(6):653-664.
APA He, Li-Ping.(2009).Foreground removal of 21 cm fluctuation with multifrequency fitting.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,9(6),653-664.
MLA He, Li-Ping."Foreground removal of 21 cm fluctuation with multifrequency fitting".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 9.6(2009):653-664.
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