Toward empirical constraints on the global redshifted 21 cm brightness temperature during the epoch of reionization

Judd D. Bowman, Alan E.E. Rogers, Jacqueline N. Hewitt

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Preliminary results are presented from a simple, single-antenna experiment designed to measure the all-sky radio spectrum between 100 and 200 MHz. The system used an internal comparison-switching scheme to reduce nonsmooth instrumental contaminants in the measured spectrum to 75 mK. From the observations, we place an initial upper limit of 450 mK on the relative brightness temperature of the redshifted 21 cm contribution to the spectrum due to neutral hydrogen in the intergalactic medium (IGM) during the epoch of reionization, assuming a rapid transition to a fully ionized IGM at z = 8. With refinement, this technique should be able to distinguish between slow and fast reionization scenarios. To constrain the duration of reionization to Δz > 2, the systemic residuals in the measured spectrum must be reduced to 3 mK.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalAstrophysical Journal
Volume676
Issue number1
DOIs
StatePublished - Mar 20 2008
Externally publishedYes

Keywords

  • Early universe
  • Intergalactic medium
  • Radio lines: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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