Searching for Stringy Topologies in the Cosmic Microwave Background

TL;DR

This paper investigates the potential observable effects of a stringy orbifold topology on the cosmic microwave background, identifying a unique signature and analyzing WMAP data to search for evidence.

Contribution

It introduces the concept of an orbifold topology in the universe and examines its observable imprints on the CMB, including a specific signature and data analysis.

Findings

Identified a potential circle signature in WMAP data.

Placed a lower bound on the distance to an orbifold point.

Found no conclusive evidence for an orbifold in the data.

Abstract

We consider a universe with a non-classical stringy topology that has fixed points. We concentrate on the simplest example, an orbifold point, and study its observable imprints on the cosmic microwave background (CMB). We show that an orbifold preserves the Gaussian nature of the temperature fluctuations, yet modifies the angular correlation function. A direct signature of an orbifold is a single circle in the CMB that is invariant under rotation by 180 degrees. Searching the 7-year ILC map of WMAP, we find one candidate circle with high statistical significance. However, a closer look reveals that the temperature profile does not fit an orbifold. We place a lower bound on the distance to an orbifold point at ~85% of the distance to the surface of last scattering.