Journal Article

Ionized bubble number count as a probe of non-Gaussianity

Hiroyuki Tashiro and Naoshi Sugiyama

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 420, issue 1, pages 441-446
Published in print February 2012 | ISSN: 0035-8711
Published online January 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.20049.x
Ionized bubble number count as a probe of non-Gaussianity

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The number count of ionized bubbles on a map of 21-cm fluctuations with the primordial non-Gaussianity is investigated. The existence of the primordial non-Gaussianity modifies the re-ionization process, because the formation of collapsed objects, which could be the source of re-ionization photons, is affected by the primordial non-Gaussianity. In this paper, the abundance of ionized bubbles is calculated by using a simple analytic model with the local type of the primordial non-Gaussianity, which is parametrized by fNL. In order to take into account the dependence of the number count on the size of ionized bubbles and the resolution of the observation instrument, a threshold parameter Bb which is related to the the surface brightness temperature contrast of an ionized bubble is introduced. We show the potential to put the constraint on fNL from the number count by future observations such as Low Frequency Array (LOFAR) and Square Kilometre Array (SKA).

Keywords: cosmic background radiation; cosmology: theory; dark ages, reionization, first stars; large-scale structure of Universe

Journal Article.  3527 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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