Gravitational Fluctuations as an Alternative to Inflation II. CMB Angular Power Spectrum

TL;DR

This paper explores an alternative to inflation based on gravitational fluctuations, demonstrating good consistency with cosmological data and extending previous work to include CMB angular power spectrum predictions.

Contribution

It introduces a nonperturbative quantum field-theoretical approach to explain cosmological power spectra, including the CMB, without relying on inflation models.

Findings

Good agreement between theory and recent cosmological data.

Constraints on fundamental parameters from data.

Potential to test the model with future measurements.

Abstract

Power spectra always play an important role in the theory of inflation. In particular, the ability to reproduce the galaxy matter power spectrum and the CMB temperature angular power spectrum coefficients to high accuracy is often considered a triumph of inflation. In our previous work, we presented an alternative explanation for the matter power spectrum based on nonperturbative quantum field-theoretical methods applied to Einstein's gravity, instead of inflation models based on scalar fields. In this work, we review the basic concepts and provide further in-depth investigations. We first update the analysis with more recent data sets and error analysis, and then extend our predictions to the CMB angular spectrum coefficients, which we did not consider previously. Then we investigate further the potential freedoms and uncertainties associated with the fundamental parameters that are part of this picture, and show how recent cosmological data provides significant constraints on these quantities. Overall, we find good general consistency between theory and data, even potentially favoring the gravitationally-motivated picture at the largest scales. We summarize our results by outlining how this picture can be tested in the near future with increasingly accurate astrophysical measurements.