Fitting BICEP2 with defects, primordial gravitational waves and dust

TL;DR

This paper explores whether cosmic defects, inflationary gravitational waves, and dust foregrounds can explain the BICEP2 B-mode polarization signal, finding defects alone are insufficient but can improve fits when combined with other sources.

Contribution

It introduces combined models of defects, gravitational waves, and dust to better fit BICEP2 data and derives new constraints on defects within these models.

Findings

Defects alone poorly fit BICEP2 data.

Defects improve fit at higher multipoles when combined with other sources.

New constraints on defects are derived from combined models.

Abstract

In this work we discuss the possibility of cosmic defects being responsible for the B-mode signal measured by the BICEP2 collaboration. We also allow for the presence of other cosmological sources of B-modes such as inflationary gravitational waves and polarized dust foregrounds, which might contribute to or dominate the signal. On the one hand, we find that defects alone give a poor fit to the data points. On the other, we find that defects help to improve the fit at higher multipoles when they are considered alongside inflationary gravitational waves or polarized dust. Finally, we derive new defect constraints from models combining defects and dust. This proceeding is based on previous works [1,2].