A Pop III generated dust screen at z~16

TL;DR

This paper explores the possibility that the cosmic microwave background (CMB) at redshift ~16 could be explained by scattering through a dust screen generated by Population III stars, challenging the standard recombination model.

Contribution

It introduces the idea that Pop III star-generated dust could account for CMB anisotropies at high redshift, providing an alternative to the standard recombination scenario.

Findings

Planck data hints at a 2-4% frequency dependence in the CMB spectrum.

A dust scattering model at z~16 remains consistent with current observations.

Upcoming measurements could distinguish between dust scattering and recombination scenarios.

Abstract

The search for alternative cosmological models is largely motivated by the growing discordance between the predictions of LCDM and the ever improving observations, such as the disparity in the value of H_0 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 Pop III generated dust screen, cannot yet be ruled out by the current data. Indeed, the Planck measurements provide a hint of a ~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.