Constraining isocurvature perturbations with the 21 cm emission from minihaloes

Takeuchi, Yoshitaka; Chongchitnan, Sirichai

Abstract

We investigate the effects of isocurvature perturbations on the 21 cm radiation from minihaloes (MHs) at high redshifts and examine constraints on the isocurvature amplitude and power spectrum using the next generation of radio telescopes such as the Square Kilometre Array. We find that there is a realistic prospect of observing the isocurvature imprints in the 21 cm emission from MHs, but only if the isocurvature spectral index is close to 3 (i.e. the spectrum is blue). When the isocurvature fraction increases beyond ∼10 per cent of the adiabatic component, we observe an unexpected decline in the 21 cm fluctuations from small-mass MHs, which can be explained by the incorporation small MHs into larger haloes. We perform a detailed Fisher-matrix analysis and conclude that the combination of future cosmic microwave background and 21 cm experiments (such as CMBPol and the Fast Fourier Transform Telescope) is ideal in constraining the isocurvature parameters, but will stop short of distinguishing between cold dark matter and baryon types of isocurvature perturbations, unless the isocurvature fraction is large and the spectrum is blue.

Citation

Takeuchi, Y., & Chongchitnan, S. (2014). Constraining isocurvature perturbations with the 21 cm emission from minihaloes. Monthly notices of the Royal Astronomical Society, 439(1), 1125-1135. https://doi.org/10.1093/mnras/stu059

• Acceptance Date: Jan 8, 2014
• Online Publication Date: Feb 5, 2014
• Publication Date: Mar 21, 2014
• Deposit Date: Apr 12, 2016
• Publicly Available Date: Apr 12, 2016
• Journal: Monthly notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 439
• Issue: 1
• Pages: 1125-1135
• DOI: https://doi.org/10.1093/mnras/stu059
• Keywords: Cosmology : theory; Diffuse radiation; Radio lines : general
• Public URL: https://hull-repository.worktribe.com/output/435756
• Publisher URL: http://mnras.oxfordjournals.org/content/439/1/1125
• Additional Information: This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.