Position Space CMB Anomalies from Multi-Stream Inflation

TL;DR

This paper investigates how temporary domain walls during multi-stream inflation create observable anisotropies in the CMB, including preferred directions, multipole suppression, and alignments, linking inflationary dynamics to potential CMB anomalies.

Contribution

It models the effects of domain walls in multi-stream inflation on CMB anisotropies, providing a theoretical framework for observed anomalies.

Findings

Domain walls induce a preferred direction in the sky.

Suppression and alignment of multipoles are generated.

Potential explanations for hemispherical asymmetry and cold spot.

Abstract

Temporary domain walls are produced during the bifurcation era of multi-stream inflation. The observational effects from such a domain wall to spectator field perturbations are calculated, and we expect the inflationary perturbations share similarities with the case of spectator field. A domain wall induces a preferred direction in the sky, affecting the angular distribution of perturbations. A correlated suppression of multipoles together with an alignment of multipole moments on the preferred direction are generated. Other observational aspects of multi-stream inflation, including hemispherical asymmetry and cold spot are also briefly reviewed.