The effect of primordial black holes on 21 cm fluctuations

Understand

The 21 cm signal produced by non-evaporating primordial black holes (PBHs) is investigated.

• X-ray photons emitted by accretion of matter onto a PBH ionize and heat the intergalactic medium (IGM) gas near the 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 depending on the PBH mass.