Influences of accreting primordial black holes on the global 21cm signal in the dark ages

Baryonic matter can be accreted on to primordial back holes (PBHs) formed in the early Universe. The radiation from accreting PBHs is capable of altering the evolution of the intergalactic medium (IGM), leaving marks on the global 21 cm signal in the dark ages. For accreting PBHs with mass M-PBH = 10(3)(10(4)) M-circle dot and mass fraction f(PBH) = 10(-1)(10(-3)), the brightness temperature deviation Delta delta T-b reaches similar to 18 (26) mK at redshift z similar to 90 (nu similar to 16 MHz), and the gradient of the brightness temperature d delta T-b/d nu reaches similar to 0.8 (0.5) mK MHz(-1) at frequency nu similar to 28 MHz (z similar to 50). For larger PBHs with higher mass fraction, the brightness temperature deviation is larger in the redshift range z similar to 30-300 (nu similar to 5-46 MHz), and the gradient is lower at the frequency range nu similar to 20-60 MHz (z similar to 23-70). It is impossible to detect these low-frequency radio signals from the Earth due to the influence of the Earth's ionosphere. However, after taking care of the essential factors properly, e.g. the foreground and interference, a future radio telescope in lunar orbit or on the farside surface of the Moon has a chance of detecting the global 21 cm signals impacted by accreting PBHs and distinguishing them from the standard model.

Automated summary

Accreting PBHs can alter the evolution of the IGM, impacting the global 21 cm signal during the dark ages. Future radio telescopes in lunar orbit or on the farside of the Moon may detect these signals and distinguish them from the standard model after accounting for essential factors like foreground and interference.