Cosmology - Cosmic Microwave Background (CMB)

Cosmic Microwave Background (CMB)

The Cosmic Microwave Background (CMB) is the remnant of the hot and dense early phases of the Universe. Its blackbody spectrum peaks around 2 mm (150 GHz) and its intensity dominates the high Galactic latitude sky at all wavelengths from about 20 cm to about 500 µm. Soon after the its discovery, in 1965, it was realized that the density fluctuations that seeded all the structure seen today must have imprinted tiny anisotropies in the CMB temperature, first detected in 1992 by NASA's COBE satellite. The power spectrum of CMB anisotropies encodes detailed information on the key cosmological parameters. An impressive series of experiments, culminating in the presently flying NASA's Wilkinson Anisotropy Probe (WMAP), have led to determine that the universe is close to spatially flat, it is dominated by dark energy, accounting for about 70% of the present cosmic energy density, by dark matter comprising about 85% of the matter density, and that primordial fluctuations had a nearly scale-invariant spectrum, consistent with having emerged from a primordial inflationary phase. In the inflationary scenario, vacuum energy dominated the energy density of the universe during its first moments, driving an exponential expansion which stretched a microscopic patch to a size much larger than our visible universe and making its geometry flat to high accuracy.

Primordial inflation also allows us to put constrains on the origin and the statistical properties of the primordial perturbations. The tremendous inflationary expansion bridges the gap between the subatomic length scales, on which quantum fluctuations are generated, and astrophysical scales, relating the seeds of the structure we observe in the universe to quantum fluctuations originated some 10^(-35) seconds after the big bang. In other words, from CMB anisotropies, that are directly related to the primordial density fluctuations, we learn about physical processes occurring at extreme energies, unattainable in any conceivable accelerator on Earth. Thus studies of the CMB bring us to the deepest questions about the origin of the universe. Although the inflationary scenario provides an impressive set of answers, the underlying physics is not well understood, and we need to dig more deeply into the extraordinary wealth of information contained in CMB maps.The next step in this direction is the Planck satellite, developed by the European Space Agency as the definitive mission for the study of CMB temperature anisotropy on scales down to 5 arcmin and as big step forward towards all-sky measurements of CMB polarization. Within the international Planck Consortium, the Padova group is leading the "component separation" effort for the Planck Low Frequency Instrument. The aim of this effort is, on one side, the cleaning of the CMB maps produced by Planck in the frequency range 30 - 860 GHz from the astrophysical signals superposed on it, and, on the other side, the reconstruction, as accurately as possible, of each individual foreground component, which has its own astrophysical interest.

Cosmic Microwave Background (CMB) - PAST STUDIES


Il notiziario online dell'Istituto Nazionale di Astrofisica
  • Le osservazioni con il Very Large Telescope dell'Eso, in Cile, e altri osservatori in tutto il mondo mostrano che questo oggetto singolare ha viaggiato nello spazio per milioni di anni prima dell'incontro causale con il Sistema solare. I risultati oggi su Nature

  • Quanto la ionosfera è influenzata dall'attività solare? Gli impulsi emessi durante i brillamenti solari arrivano fino allo strato "elettrificato" dell'atmosfera terrestre e possono disturbare in maniera significativa i satelliti che si trovano nell’orbita geostazionaria

  • Dopo l’anno della luce e la settimana della luce, la radiazione elettromagnetica ha ora anche una sua giornata internazionale. La data scelta dall’Unesco è quella della prima realizzazione artigianale di un laser al cristallo di rubino, avvenuta il 16/5/1960

  • Dal 20 novembre al 17 dicembre 2017 è possibile inviare la propria candidatura all’Agenzia spaziale europea per la call Young Graduate Trainees: un programma rivolto a laureandi e neolaureati, in varie discipline, per lavorare un intero anno a progetti spaziali

  • Un gruppo di ricerca giapponese ha scoperto che l’emissione in microonde del Sole, durante i cinque cicli undecennali dell’attività magnetica misurati finora, è caratterizzati da minimi sempre uguali, nonostante le grandi variazioni dei massimi

  • Fra i 13 winter-over che oggi s’imbarcano per il Polo Sud c’è anche Marco Buttu dell'Inaf di Cagliari. Media Inaf lo seguirà da vicino nella sua impresa polare e racconterà periodicamente la sua avventura fino al rientro, previsto per dicembre 2018, dopo ben tredici mesi di isolamento fra i ghiacci

Go to top

We use cookies to improve our website and your experience when using it. Cookies used for the essential operation of the site have already been set. To find out more about the cookies we use and how to delete them, see our privacy policy.

I accept cookies from this site.

EU Cookie Directive Module Information