Scale-dependent CMB asymmetry from primordial configuration

TL;DR

This paper proposes that a pre-existing topological defect can generate the observed hemispherical power asymmetry in the CMB, with scale dependence explained by modulation mechanisms like the curvaton, using the δN formalism.

Contribution

It introduces a model where primordial topological defects cause CMB asymmetry, incorporating scale dependence through modulation mechanisms, analyzed via the δN formalism.

Findings

Defect configurations can source CMB asymmetry prior to inflation.

Modulation mechanisms explain the scale dependence of asymmetry.

The δN formalism effectively models the primordial defect effects.

Abstract

We demonstrate that a topological defect can explain the hemispherical power asymmetry of the CMB. The first point is that a defect configuration, which already exists prior to inflation, can source asymmetry of the CMB. The second point is that modulation mechanisms, such as the curvaton and other modulation mechanisms, can explain scale-dependence of the asymmetry. Using a simple analysis of the $\delta N$ formalism, we show models in which scale-dependent hemispherical power asymmetry is explained by primordial configuration of a defect.