Foreground science knowledge and prospects

Aurélien A. Fraisse, Jo Anne C. Brown, Gregory Dobler, Jessie L. Dotson, Bruce T. Draine, Priscilla C. Frisch, Marijke Haverkorn, Christopher M. Hirata, Ronnie Jansson, Alex Lazarian, Antonio Mario Magalhães, André Waelkens, Maik Wolleben

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Scopus citations


Detecting "B-mode" (i.e., divergence free) polarization in the Cosmic Microwave Background (CMB) would open a new window on the very early Universe. However, the polarized microwave sky is dominated by polarized Galactic dust and synchrotron emissions, which may hinder our ability to test inflationary predictions. In this paper, we report on our knowledge of these "Galactic foregrounds", as well as on how a CMB satellite mission aiming at detecting a primordial B-mode signal ("CMBPol") will contribute to improving it. We review the observational and analysis techniques used to constrain the structure of the Galactic magnetic field, whose presence is responsible for the polarization of Galactic emissions. Although our current understanding of the magnetized interstellar medium is somewhat limited, dramatic improvements in our knowledge of its properties are expected by the time CMBPol flies. Thanks to high resolution and high sensitivity instruments observing the whole sky at frequencies between 30 GHz and 850 GHz, CMBPol will not only improve this picture by observing the synchrotron emission from our galaxy, but also help constrain dust models. Polarized emission from interstellar dust indeed dominates over any other signal in CMBPol's highest frequency channels. Observations at these wavelengths, combined with groundbased studies of starlight polarization, will therefore enable us to improve our understanding of dust properties and of the mechanism(s) responsible for the alignment of dust grains with the Galactic magnetic field. CMBPol will also shed new light on observations that are presently not well understood. Morphological studies of anomalous dust and synchrotron emissions will indeed constrain their natures and properties, while searching for fluctuations in the emission from heliospheric dust will test our understanding of the circumheliospheric interstellar medium. Finally, acquiring more information on the properties of extra-Galactic sources will be necessary in order to maximize the cosmological constraints extracted from CMBPol's observations of CMB lensing.

Original languageEnglish (US)
Title of host publicationCMB Polarization Workshop
Subtitle of host publicationTheory and Foregrounds - CMBPol Mission Concept Study
Number of pages46
StatePublished - 2009
EventCMB Polarization Workshop: Theory And Foregrounds - Batavia, IL, United States
Duration: Jun 23 2008Jun 26 2008

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherCMB Polarization Workshop: Theory And Foregrounds
Country/TerritoryUnited States
CityBatavia, IL

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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