Planck 2013 results. I. Overview of products and scientific results

The European Space Agency’s Planck satellite, dedicated to studying the early universe and its subsequent evolution, was launched on 14 May 2009 and has been surveying the microwave and submillimetre sky continuously since August 2009. In March 2013, ESA and the Planck Collaboration publicly released the initial cosmology products based on the the first 15.5 months of Planck operations, along with a set of scientific and technical papers and a web-based explanatory supplement. This paper describes the mission and its performance, and gives an overview of the processing and analysis of the data, the characteristics of the data, the main scientific results, and the science data products and papers in the release. The science products include a set of specialized maps of the cosmic microwave background, maps of Galactic and extragalactic extended foregrounds, a catalogue of compact Galactic and extragalactic sources, and a list of sources detected through the Sunyaev-Zeldovich effect. The likelihood code used to assess cosmological models against the Planck data and a lensing likelihood are described. Scientific results include robust support for the standard, six parameter ΛCDM model of cosmology and improved measurements for the parameters that define this model, including a highly significant deviation from scale invariance of the primordial power spectrum. The Planck values for some of these parameters and others derived from them are significantly different from those previously determined. Several large scale anomalies in the CMB temperature distribution detected earlier by WMAP are confirmed with higher confidence. Plancksets new limits on the number and mass of neutrinos, and has measured gravitational lensing of CMB anisotropies at 25σ. Planck finds no evidence for non-Gaussian statistics of the CMB anisotropies. There is some tension between Planck and WMAP results; this is evident in the power spectrum and results for some of the cosmology parameters. In general, Planck results agree well with results from the measurements of baryon acoustic oscillations. Because the analysis of Planck polarization data is not yet as mature as the analysis of temperature data, polarization results are not released. We do, however, graphically illustrate the robust detection of the E-mode polarization signal around CMB hotand cold-spots.