Puzzling initial conditions in the R_h=ct model

TL;DR

This paper investigates whether the $R_h=ct$ cosmological model can generate the primordial power spectrum needed to explain CMB observations, finding significant theoretical challenges in defining quantum perturbations within this framework.

Contribution

It explores the generation of primordial quantum fluctuations in the $R_h=ct$ model, considering scalar field dominance and early inflation, and highlights fundamental issues in characterizing perturbations.

Findings

Deep issues in defining quantum perturbations in $R_h=ct$

Challenges in matching observed CMB anisotropies

Incompatibility with standard primordial spectrum generation

Abstract

In recent years, some studies have drawn attention to the lack of large-angle correlations in the observed cosmic microwave background (CMB) temperature anisotropies with respect to that predicted within the standard $\Lambda$CDM model. Lately, it has been argued that such a lack of correlations could be explained in the framework of the so-called $R_h=ct$ model without inflation. The aim of this work is to study whether there is a mechanism to generate, through a quantum field theory, the primordial power spectrum presented by these authors. Specifically, we consider two different scenarios: first, we assume a scalar field dominating the early Universe in the $R_h=ct$ cosmological model, and second, we deal with the possibility of adding an early inflationary phase to the mentioned model. During the analysis of the consistency between the predicted and observed amplitudes of the CMB temperature anisotropies in both scenarios, we run into deep issues which indicate that it is not clear how to characterize the primordial quantum perturbations within the $R_h=ct$ model.