Observational Manifestations of Primordial Objects in the Early Universe Through the Hydrogen Subordinate Lines

A new mechanism for the formation of spectral–spatial distortions in cosmic microwave background radiation near primordial massive compact objects (such as primordial black holes) at redshifts from z∼1000 to ∼100 is proposed. After hydrogen recombination, the radiation from these objects leads to a significant increase in the population of hydrogen subordinate levels in their surrounding environment. Consequently, this allows for the observation of a Fraunhofer-like absorption spectrum in the cosmic microwave background. Such a distortion is formed due to the temperature difference between matter and relic radiation at the corresponding epoch. Ultimately, we should observe circular absorption or emission features around the objects with small angular sizes. These subordinate hydrogen lines currently lie in the radio wavelength range. Estimates indicate that the effect under consideration is accessible for the observations with planned large radiotelescopes. The possibility of the proposed mechanism lies in the ability of an object (e.g., accretion disk around black hole) to emit few-eV photons that populate the n=2,3,4 and higher levels of hydrogen, enabling the required excitation.