An improved method for 21-cm foreground removal

Adrian Liu, Max Tegmark, Judd Bowman, Jacqueline Hewitt, Matias Zaldarriaga

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


21-cm tomography is expected to be difficult in part because of serious foreground contamination. Previous studies have found that line-of-sight approaches are capable of cleaning foregrounds to an acceptable level on large spatial scales, but not on small spatial scales. In this paper, we introduce a Fourier space formalism for describing the line-of-sight methods, and use it to introduce an improved new method for 21-cm foreground cleaning. Heuristically, this method involves fitting foregrounds in Fourier space using weighted polynomial fits, with each pixel weighted according to its information content. We show that the new method reproduces the old one on large angular scales, and gives marked improvements on small scales at essentially no extra computational cost.

Original languageEnglish (US)
Pages (from-to)401-406
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Sep 2009
Externally publishedYes


  • Early Universe
  • Methods: Data analysis
  • Radio lines: General
  • Techniques: Interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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