CMB Angular Power Spectrum from Correlated Primordial Fluctuation

TL;DR

This paper explores the impact of correlated primordial density fluctuations on the CMB angular power spectrum, showing that correlations alter the spectrum's amplitude in a way that can be constrained by observational data.

Contribution

It introduces a model where primordial Fourier modes are correlated, deviating from the standard Gaussian assumption, and calculates the resulting effects on the CMB power spectrum.

Findings

Correlation reduces the amplitude of the CMB power spectrum.

Different multipoles $l$ are affected differently by the correlations.

The model provides a way to constrain primordial correlations from data.

Abstract

The usual inflationary scenario predicts a Gaussian random primordial density fluctuation, different Fourier modes of which do not correlate with each other. In this paper we propose a correlation between these different modes. A simple case is that these different Fourier modes correlate with each other following a Gaussian function. For such a primordial density fluctuation we calculate the CMB angular power spectrum and find that its amplitude decreases but the decrease is different for different $l$. This feature can be used to constrain the the correlation strength from the real data.