An overview of the Planck results from A&A

Planck

The Planck satellite was launched in May 2009. With the highest accuracy to date, it measures the remnants of the radiation that filled the Universe immediately after the Big Bang. It is the oldest light in the Universe, emitted when it was 380000 years old. This light is observed today as the cosmic microwave background (CMB). Its maximum intensity is at about 150 GHz (2 mm), and its temperature about 3K. The study of the CMB is currently a very active field of research in cosmology because it provides strong constraints on the cosmological models. In particular, observations of the CMB confirms the key prediction of the Big Bang model and, more precisely, of what cosmologists call the concordance model of cosmology.

Planck was designed to measure the emission from the entire sky at nine distinct wavelengths, ranging from the radio (1 cm) to the far-infrared (300 microns). Several distinct sources of emission ─ both of Galactic and extragalactic origin ─ contribute to the features observed in each of the nine images shown here. Radio emissions from the Milky Way are most prominent at the longest wavelengths, and thermal dust emission at the shortest. Other galaxies contribute to the mix, mostly as unresolved sources. In the middle of Planck’s wavelength range, the CMB dominates the sky at intermediate and high Galactic latitudes. The spectral and spatial signatures of all these sources are used to extract an all-sky image of the tiny temperature anisotropies of the CMB with unprecedented accuracy. The properties of these fluctuations are used to derive the parameters characterizing our Universe at early times.

Image credit and link to Astronomy & Astrophysics special feature on Planck 2013 results: Astronomy & Astrophysics, volume 571, November 2014. Table of contents of the A&A special feature (free access).

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