Measuring CMB non-Gaussianity as a probe of Inflation and Cosmic Strings

TL;DR

This paper explores how non-Gaussian features in the cosmic microwave background and large-scale structure can reveal insights into inflation models and the presence of cosmic strings, using advanced correlation function analysis.

Contribution

It introduces a formalism for measuring four-point correlation functions (trispectra) in the CMB and applies it to probe non-Gaussian signals from inflation and cosmic strings.

Findings

Detection of non-Gaussian signals in the CMB and large-scale structure.

Methodology for measuring trispectra using CMB data.

Insights into inflationary models and cosmic string signatures.

Abstract

The leading candidate for the very early universe is described by a period of rapid expansion known as inflation. While the standard paradigm invokes a single slow-rolling field, many different models may be constructed which fit the current observational evidence. In this work we outline theoretical and observational studies of non-Gaussian fluctuations produced by models of inflation and by cosmic strings - topological defects that may be generated in the very early universe during a phase transition. In particular, we consider the imprint of cosmic strings on the cosmic microwave background (CMB) and describe a formalism for the measurement of general four-point correlation functions, or trispectra, using the CMB. In addition we describe the application of our methodology to non-Gaussian signals imprinted in the large scale structure of the universe. Such deviations from Gaussianity are generally expressed in terms of the so-called bispectrum and trispectrum.