The 21-cm radiation from minihaloes as a probe of small primordial non-Gaussianity

Authors

  • Sirichai Chongchitnan,

    Corresponding author
    1. Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
    2. School of Engineering, Computing and Applied Mathematics, University of Abertay Dundee, Bell Street, Dundee DD1 1HG
      E-mail: siri@astro.ox.ac.uk
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  • Joseph Silk

    1. Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
    2. Institut d’Astrophysique, UPMC, 98bis Boulebard Arago, Paris 75014, France
    3. Department of Physics and Astronomy, The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218, USA
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E-mail: siri@astro.ox.ac.uk

ABSTRACT

We present a new probe of primordial non-Gaussianity via the 21-cm radiation from minihaloes at high redshifts. We calculate the fluctuations in the brightness temperature (measured against the cosmic microwave background) of the 21-cm background from minihaloes containing H i at redshift ∼6–20, and find a significant enhancement due to small non-Gaussianity with amplitude fNL ≲ 1. This enhancement can be attributed to the non-linear bias which is strongly increased in the presence of non-Gaussianity. We show that our results are robust against changes in the assumed mass function and some physical aspects of minihalo formation, but are nevertheless sensitive to the presence of strong radiation sources within or around the minihaloes. Our findings are relevant for constraining and searching for small primordial non-Gaussianity with upcoming radio telescopes such as Low-Frequency Array (LOFAR) and Square Kilometre Array (SKA).

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