Global signal in the redshifted hydrogen 21-cm line from the Dark Ages and Cosmic Dawn: Dependence on the nature of dark matter and modeling of first light

TL;DR

This study models the global 21-cm hydrogen line signal during the Dark Ages and Cosmic Dawn, showing its dependence on dark matter properties and early light sources, to help constrain cosmological models.

Contribution

It provides a detailed analysis of how the 21-cm line profile depends on dark matter characteristics and early universe radiation, aiding in constraining dark matter and astrophysical models.

Findings

Dark Ages signal is highly sensitive to dark matter parameters.

Cosmic Dawn signal depends on the spectral energy distribution of first sources.

Observations can constrain dark matter and early universe models.

Abstract

We estimate the global signal in the redshifted hyperfine structure line 21 cm of hydrogen atoms formed during the Dark Ages and Cosmic Dawn epochs. The evolution of the brightness temperature in this line was computed to study its dependence on the physical conditions in the intergalactic medium. We show that the profile of this line crucially depends on the temperature and ionization of baryonic matter as well as the spectral energy distribution of radiation from the first sources. The cosmological models with the self-annihilating and decaying dark matter with allowable parameters by current observational data, as well as the model of the first light which is consistent with the observational data on reionization were considered. The results show that the Dark Ages part of profile is very sensitive to the parameters of self-annihilating and decaying dark matter particles, while the Cosmic Dawn part of profile is very sensitive also to the spectral energy distribution of radiation from the first sources. It was concluded that only compatible observations of the redshifted 21 cm line in the decameter and meter wavelength range, formed during the Dark Ages and Cosmic Dawn, will make it possible to constrain the parameters of dark matter models and astrophysical models of the first sources based on the radiotomography of the young Universe.