paper

Constraining warm dark matter with 21 cm line fluctuations due to minihalos

arXiv:1401.5563 · doi:10.1088/1475-7516/2014/08/007

Abstract

Warm dark matter (WDM) with mass m_WDM = O(1) keV has long been discussed as a promising solution for discrepancies between cosmic structures observed at small scales and predications of the concordance CDM model. Though several cosmological observations such as the Lyman-alpha forest have already begun to constrain the range of m_WDM, WDM is yet to be fully excluded as a solution for these so-called small-scale problems. In this paper, we study 21 cm line fluctuations from minihalos in a WDM model and evaluate constraints on m_WDM for future cosmological 21 cm surveys, such as SKA and FFTT. We show that, since WDM with mass m_WDM>10 keV decreases the abundance of minihalos by suppressing the matter power spectrum on small scales via free-streaming, such WDM can significantly affect the resultant 21 cm line fluctuations from minihalos. We find that if the 21 cm signal from minihalos can be observed above z>5, SKA and FFTT can give lower bounds m_WDM>24 keV and 31 keV, respectively, which are tighter than the current constraint. These future 21 cm surveys might be able to rule out a WDM model as a solution of small-scale problems.

18 pages, 8 figures, 2 tables; accepted for publication in JCAP

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