Footprints of Loop I on Cosmic Microwave Background Maps

TL;DR

This paper investigates the influence of the nearby supernova remnant Loop I on large-scale cosmic microwave background maps, confirming its traces in WMAP and Planck data, which impacts the interpretation of primordial signals.

Contribution

It provides new evidence of Loop I's imprint on CMB maps, highlighting the importance of Galactic foregrounds in cosmological analyses.

Findings

Loop I traces are present in WMAP 9-year maps.

SMICA maps from Planck also show Loop I signatures.

Foreground contamination affects primordial B-mode polarization searches.

Abstract

Cosmology has made enormous progress through studies of the cosmic microwave background, however the subtle signals being now sought such as B-mode polarisation due to primordial gravitational waves are increasingly hard to disentangle from residual Galactic foregrounds in the derived CMB maps. We revisit our finding that on large angular scales there are traces of the nearby old supernova remnant Loop I in the WMAP 9-year map of the CMB and confirm this with the new SMICA map from the Planck satellite.