A clear view of 'relic' radiation
Understanding and measuring astrophysical foreground emission, such as diffuse galactic emission, has become an important topic in CMB data analysis. Future, ultra-sensitive CMB experiments are expected to detect polarised gravitational waves arising from cosmic inflation. However, their B-mode polarisation is very weak and requires precision greater than 1 microkelvin. The EU-funded project 'Accurate foreground characterisation for future CMB experiments' (CMBFOREGROUNDS) played a major role in using observations and data analyses from several CMB/foreground experiments. Its aim was to measure and remove foreground emissions, which required combining data from multiple instruments to obtain reliable B-mode measurements. CMBFOREGROUNDS had the necessary background (from other projects in which the coordination institution was involved) to understand ground spillover, which is a major limitation for producing polarisation maps. Based on some first CMB maps showing the faint synchrotron emission, the project sought to also provide reliable ones for the coming two years. A paper was prepared that contained a first analysis of the main diffuse galactic foreground components by combining the latest full-sky microwave surveys.
