Bright source subtraction requirements for redshifted 21cm measurements

A. Datta, J. D. Bowman, C. L. Carilli

Research output: Contribution to journalArticlepeer-review

216 Scopus citations


The Hi 21cm transition line is expected to be an important probe into the cosmic dark ages and epoch of reionization. Foreground source removal is one of the principal challenges for the detection of this signal. This paper investigates the extragalactic point source contamination and how accurately bright sources (≳1 Jy) must be removed in order to detect 21 cm emission with upcoming radio telescopes such as the Murchison Widefield Array. We consider the residual contamination in 21cm maps and power spectra due to position errors in the sky model for bright sources, as well as frequency-independent calibration errors. We find that a source position accuracy of 0.1 arcsec will suffice for detection of the Hi power spectrum. For calibration errors, 0.05% accuracy in antenna gain amplitude is required in order to detect the cosmic signal. Both sources of subtraction error produce residuals that are localized to small angular scales, k&butam;≳ 0.05 Mpc-1, in the two-dimensional power spectrum.

Original languageEnglish (US)
Pages (from-to)526-538
Number of pages13
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 20 2010
Externally publishedYes


  • Early universe
  • Intergalactic medium
  • Methods: data analysis
  • Radio lines: general
  • Techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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