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

News – MEDIA INAF

Il notiziario online dell'Istituto Nazionale di Astrofisica
  • Un studio pubblicato su Nature, basato sulla Renaissance Simulation, presenta una nuova teoria sulla nascita dei primi buchi neri massicci, secondo cui condizioni particolari di aggregazione di materia oscura avrebbero favorito la formazione di buchi neri a scapito della formazione stellare

  • Si intitola “Astri perseguitati” la conferenza-concerto di Fabrizio Bònoli e Marco Padovani in programma domenica 27 a Firenze, nella biblioteca dell’Inaf – Osservatorio astrofisico di Arcetri, in occasione del Giorno della Memoria

  • Includendo Alma in una rete mondiale di radiotelescopi, gli astronomi hanno scoperto che l’emissione radio del buco nero supermassiccio che si trova al centro della nostra galassia proviene da una regione di appena un trentamilionesimo di grado: molto più piccola del previsto. Questo potrebbe anche indicare che il getto radio della sorgente è puntato quasi direttamente verso la Terra. Tutti i dettagli della ricerca su Astrophysical Journal

  • In attesa che il team della missione Hayabusa-2 decida il punto migliore in cui prelevare il campione di terreno da riportare a terra, tredici regioni dell’asteroide Ryugu hanno ora delle denominazioni ufficiali, derivate da racconti tradizionali per l’infanzia

  • Il Very Large Telescope dell’Eso ha catturato il debole, effimero bagliore che emana dalla nebulosa planetaria Eso 577-24: un guscio di gas ionizzato incandescente destinato ad affievolirsi fino a sparire nell’arco di 10mila anni

  • Usando i dati della sonda spaziale Cassini della Nasa, i ricercatori hanno determinato la durata esatta di un giorno su Saturno, pari a 10 ore, 33 minuti e 38 secondi. La risposta a questo mistero scientifico era nascosta nei suoi anelli, che risentono delle oscillazioni del campo gravitazionale provocate da vibrazioni all’interno del pianeta. Tutti i dettagli sono riportati su Astrophysical Journal.

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