A TECHNIQUE FOR FOREGROUND SUBTRACTION IN REDSHIFTED 21 cm OBSERVATIONS

Journal Article · Fri Apr 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/749/2/164· OSTI ID:22020379

Cho, Jungyeon ^[1]; Lazarian, A ^[2]; Timbie, Peter T ^[3]

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1. Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)
2. Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)
3. Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

One of the main challenges for future 21 cm observations is to remove foregrounds which are several orders of magnitude more intense than the H I signal. We propose a new technique for removing foregrounds of the redshifted 21 cm observations. We consider multi-frequency interferometer observations. We assume that the 21 cm signals in different frequency channels are uncorrelated and the foreground signals change slowly as a function of frequency. When we add the visibilities of all channels, the foreground signals increase roughly by a factor of {approx}N because they are highly correlated. However, the 21 cm signals increase by a factor of {approx}{radical}N because the signals in different channels contribute randomly. This enables us to obtain an accurate shape of the foreground angular power spectrum. Then, we obtain the 21 cm power spectrum by subtracting the foreground power spectrum obtained this way. We describe how to obtain the average power spectrum of the 21 cm signal.

• OSTI ID: 22020379
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 749; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

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