Hiroyuki Tashiro, Naoshi Sugiyama
The 21 cm signal produced by non-evaporating primordial black holes (PBHs) is investigated. X-ray photons emitted by the accretion to a PBH ionize and heat intergalactic medium (IGM) gas near a PBH. Using a simple analytic model, we show that this x-ray heating can produce an observable differential 21 cm brightness temperature. The region of the observable 21 cm brightness temperature can extend to 1-10 Mpc comoving distance from a PBH with depending on the PBH mass. The angular power spectrum of 21 cm fluctuations due to PBHs is also calculated. The peak position of the angular spectrum depends on the PBH mass, while the amplitude is independent. Comparing it with the angular power spectrum caused by primordial density fluctuations, it is found that both of them become comparable if \Omega_{PBH} \sim 10^{-12} at z=30 and 10^{-13} at z=20 for the PBH mass from 10 M_\odot to 10^8 M_\odot. Finally we find that the Square Kilometer Array can detect the signal due to PBHs up to \Omega_{PBH}=10^{-9} at z=30 and 10^{-10} at z=20 for PBHs with mass from 10^2 M_\odot to 10^8 M_\odot.
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http://arxiv.org/abs/1207.6405
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