Prospects for probing dark matter particles and primordial black holes with the Square Kilometre Array using the 21 cm power spectrum at cosmic dawn*

Abstract Probing the nature of dark matter (DM) remains an outstanding problem in modern cosmology. The 21 cm signal, a sensitive tracer of neutral hydrogen during the cosmic dawn, provides a unique means to investigate DM nature during this critical epoch. The annihilation and decay of DM particles, as well as Hawking radiation of primordial black holes (PBHs), can modify the thermal and ionization histories of the early universe, leaving distinctive imprints on the 21 cm power spectrum. Therefore, the redshifted 21 cm power spectrum serves as an effective tool for investigating such DM processes. In this work, we systematically assess the potential of the upcoming Square Kilometre Array (SKA) to constrain DM and PBH parameters using the 21 cm power spectrum. Assuming 10,000 h of integration time, the SKA is projected to reach sensitivities of and for DM particles. It can also probe PBHs with masses of and abundances of . These results indicate that the SKA can place constraints on DM annihilation, decay, and PBH Hawking radiation that are up to two to three orders of magnitude stronger than current limits. Furthermore, the SKA is expected to exceed existing bounds on sub-GeV DM and probe Hawking radiation from PBHs with masses above , which are otherwise inaccessible using conventional cosmological probes. Overall, the SKA holds significant promise for advancing our understanding of both DM particles and PBHs, potentially offering new insights into the fundamental nature of DM.