Abstract The redshifted 21-cm signal from the dark ages offers a powerful probe of cosmological models and the underlying dark matter (DM) microphysics. We investigate deviations from the standard ΛCDM prediction, an absorption trough of approximately −40.6 mK at redshift z ≃ 85.6, in the context of co-SIMP (strongly interacting massive particle) DM. The co-SIMP interaction strength is encoded by the parameter Cint, incorporating the masses of DM and standard model (SM) particles, the interaction cross-section, and the amount of heat exchange between the two sectors. Increasing Cint deepens the absorption feature and shifts the trough to higher redshifts in the global signal. For Cint = 1.0, the minimum brightness temperature reaches −50.6, mK at z ≃ 86.2. The 21-cm power spectrum increases with Cint in addition to the global signal. We assess the detectability of these signatures using signal-to-noise ratio (SNR) and Fisher forecasts. The maximum SNR reaches ∼15.7 for Cint = 1.0 for the global signal. Fisher forecasts for 1,000 hours of integration time show that this model can be distinguished from a null-signal at 4.3σ and a mild 1.6σ from ΛCDM, improving by an order of magnitude for 100,000 hours. For the 21-cm power spectrum, a 5, km2 array with 1,000 hours yields a 4.63σ detection and mildly separated from the standard scenario at 1.78σ. These findings highlight the potential of the 21-cm cosmology to probe the properties of DM and demonstrate that upcoming dark ages experiments, particularly space-based and lunar observations, can offer a promising avenue to test co-SIMP models.
Paul et al. (Wed,) studied this question.