2022ApJ...941..178M

The search for alternative cosmological models is largely motivated by the growing discordance between the predictions of ΛCDM and the ever-improving observations, such as the disparity in the value of H₀ measured at low and high redshifts. One model in particular, known as the R_h = ct universe, has been highly successful in mitigating or removing all of the inconsistencies. In this picture, however, the anisotropies in the cosmic microwave background (CMB) would have emerged at a redshift z ∼ 16, rather than via fluctuations in the recombination zone at z ∼ 1080. We demonstrate here that a CMB created in the early universe, followed by scattering through a Population III-generated dust screen, is consistent with all of the current data. Indeed, the Planck measurements provide a hint of an ∼2%-4% frequency dependence in the CMB power spectrum, which would be naturally explained as a variation in the optical depth through the dust but not a Thomson scattering-dominated recombination environment. Upcoming measurements should be able to easily distinguish between these two scenarios, e.g., via the detection of recombination lines at z ∼ 1080, which would completely eliminate the dust-reprocessing idea.