Bayesian constraints on the global 21-cm signal from the Cosmic Dawn
Date Issued
2016
Author(s)
•
Zwart, J. T. L.
•
Price, D.
•
Greenhill, L. J.
•
Mesinger, A.
•
Dowell, J.
•
Eftekhari, T.
•
Ellingson, S. W.
•
Kocz, J.
•
Schinzel, F.
Abstract
The birth of the first luminous sources and the ensuing epoch of reionization are best studied via the redshifted 21-cm emission line, the signature of the first two imprinting the last. In this work, we present a fully Bayesian method, HIBAYES, for extracting the faint, global (sky-averaged) 21-cm signal from the much brighter foreground emission. We show that a simplified (but plausible) Gaussian model of the 21-cm emission from the Cosmic Dawn epoch (15 ≲ z ≲ 30), parametrized by an amplitude A_{H I}, a frequency peak ν _{H I} and a width σ _{H I}, can be extracted even in the presence of a structured foreground frequency spectrum (parametrized as a seventh-order polynomial), provided sufficient signal-to-noise (400 h of observation with a single dipole). We apply our method to an early, 19-min-long observation from the Large aperture Experiment to detect the Dark Ages, constraining the 21-cm signal amplitude and width to be -890 < A_{H I} < 0 mK and σ _{H I} > 6.5 MHz (corresponding to ∆z > 1.9 at redshift z ≃ 20) respectively at the 95-per cent confidence level in the range 13.2 < z < 27.4 (100 > ν > 50 MHz).
Volume
461
Issue
3
Start page
2847
Issn Identifier
0035-8711
Ads BibCode
2016MNRAS.461.2847B
Rights
open.access
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