CERN Accelerating science

Talk
Title	Toward an Understanding of Foreground Emission in the BICEP2 Region
Video	If you experience any problem watching the video, click the download button below Download Embed Show n. of views Mp4: 360p (presentation) 480p (presentation) 720p (presentation) 360p (presenter) Subtitles: English FrançAis Copy-paste this code into your page: <iframe width="640" height="360" frameborder="0" src="https://cds.cern.ch/video/1741689?" allowfullscreen></iframe>
Author(s)	Flauger, Raphael (speaker) (Inst. for Advanced Studies and New York University)
Corporate author(s)	CERN. Geneva
Imprint	2014-07-09. - 4697.
Series	(TH Theoretical Seminar)
Lecture note	on 2014-07-09T14:00:00
Subject category	TH Theoretical Seminar
Abstract	BICEP2 has reported the detection of a degree-scale B-mode polarization pattern in the Cosmic Microwave Background (CMB) and has interpreted the measurement as evidence for primordial gravitational waves. Motivated by the profound importance of the discovery of gravitational waves from the early Universe, I will discuss to what extent a combination of Galactic foregrounds and lensed E-modes could be responsible for the signal. I will present independent estimates of the dust polarization signal in the BICEP2 region using several different approaches. These estimates of the dust polarization signal in the BICEP2 region are consistent with each other, but the expected amplitude of the dust polarization power spectrum is uncertain by about a factor of three. The lower end of the prediction leaves room for a primordial contribution, but at the higher end the dust in combination with the standard CMB lensing signal could account for the BICEP2 observations, without requiring the existence of primordial gravitational waves. By studying the cross-correlations between the pre-Planck templates used in the BICEP2 analysis and between different versions of a data-based template, we emphasize that cross-correlations between models are likely underestimates of the contribution of foregrounds to the map. These results suggest that BICEP1 and BICEP2 data alone cannot distinguish between foregrounds and a primordial gravitational wave signal, and that future Keck Array observations at 100 GHz and Planck observations at higher frequencies will be crucial to determine whether the signal is of primordial origin. Luckily, we will not have to wait very long until this question is resolved.
Copyright/License	© 2014-2024 CERN
Submitted by	[email protected]