Journal Article

Detection and extraction of signals from the epoch of reionization using higher-order one-point statistics

Geraint J. A. Harker, Saleem Zaroubi, Rajat M. Thomas, Vibor Jelić, Panagiotis Labropoulos, Garrelt Mellema, Ilian T. Iliev, Gianni Bernardi, Michiel A. Brentjens, A. G. De Bruyn, Benedetta Ciardi, Leon V. E. Koopmans, V. N. Pandey, Andreas H. Pawlik, Joop Schaye and Sarod Yatawatta

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 393, issue 4, pages 1449-1458
Published in print March 2009 | ISSN: 0035-8711
Published online February 2009 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2008.14209.x
Detection and extraction of signals from the epoch of reionization using higher-order one-point statistics

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Detecting redshifted 21-cm emission from neutral hydrogen in the early Universe promises to give direct constraints on the epoch of reionization (EoR). It will, though, be very challenging to extract the cosmological signal (CS) from foregrounds and noise which are orders of magnitude larger. Fortunately, the signal has some characteristics which differentiate it from the foregrounds and noise, and we suggest that using the correct statistics may tease out signatures of reionization. We generate mock data cubes simulating the output of the Low Frequency Array (LOFAR) EoR experiment. These cubes combine realistic models for Galactic and extragalactic foregrounds and the noise with three different simulations of the CS. We fit out the foregrounds, which are smooth in the frequency direction, to produce residual images in each frequency band. We denoise these images and study the skewness of the one-point distribution in the images as a function of frequency. We find that, under sufficiently optimistic assumptions, we can recover the main features of the redshift evolution of the skewness in the 21-cm signal. We argue that some of these features – such as a dip at the onset of reionization, followed by a rise towards its later stages – may be generic, and give us a promising route to a statistical detection of reionization.

Keywords: methods: statistical; cosmology: theory; diffuse radiation; radio lines: general

Journal Article.  9017 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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