Utente:Vale maio/Sandbox3: differenze tra le versioni
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Additional ground-based instruments such as the [[South Pole Telescope]] in Antarctica and the proposed [[Clover (telescope)|Clover]] Project, [[Atacama Cosmology Telescope]] and the [[QUIET telescope]] in Chile will provide additional data not available from satellite observations, possibly including the B-mode polarization.
==Riduzione dei dati e analisi==
Raw CMBR data coming down from the space vehicle (i.e., WMAP) contain foreground effects that completely obscure the fine-scale structure of the Cosmic Microwave background. The fine-scale structure is superimposed on the raw CMBR data but is too small to be seen at the scale of the raw data. The most prominent of the foreground effects is the dipole anisotropy caused by the Sun's motion relative to the CMBR background. The dipole anisotropy and others due to Earth's annual motion relative to the Sun and numerous microwave sources in the galactic plane and elsewhere must be subtracted out to reveal the extremely tiny variations characterizing the fine-scale structure of the CMBR background.
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Constraints on many cosmological parameters can be obtained from their effects on the power spectrum, and results are often calculated using [[Markov Chain Monte Carlo]] sampling techniques.
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From the CMB data it is seen that our local group of galaxies (the galactic cluster that includes the Solar System's Milky Way Galaxy) appears to be moving at 627±22 km/s relative to the '''reference frame of the CMB''' (also called the '''CMB rest frame''') in the direction of galactic longitude ''l'' = 276±3°, ''b'' = 30±3°.<ref>{{cite journal|last=Kogut|first=A.|coauthors=''et al.''|year=1993|title=Dipole Anisotropy in the COBE Differential Microwave Radiometers First-Year Sky Maps|journal=[[Astrophysical Journal]]|volume=419|pages=1–6|doi=10.1086/173453|id={{arXiv|astro-ph/9312056}}}}</ref> This motion results in an anisotropy of the data (CMB appearing slightly warmer in the direction of movement than in the opposite direction)<ref>http://antwrp.gsfc.nasa.gov/apod/ap090906.html</ref>. The standard interpretation of this temperature variation is a simple velocity redshift and blueshift due to motion relative to the CMB, but alternative cosmological models can explain some fraction of the observed dipole temperature distribution in the CMB.<ref>{{cite journal|last=Inoue|first=K. T.|last2=Silk|first2=J.|year=2007|title=Local Voids as the Origin of Large-Angle Cosmic Microwave Background Anomalies: The Effect of a Cosmological Constant|journal=[[Astrophysical Journal]]|volume=664|issue=2|pages=650–659|doi=10.1086/517603|id={{arXiv|astro-ph/0612347}}}}</ref>
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With the increasingly precise data provided by WMAP, there have been a number of claims that the CMB suffers from anomalies, such as very great-scale anisotropies, anomalous alignments, and non-Gaussian distributions.<ref name="arXiv:0905.2854v2">{{cite arxiv|last=Rossmanith|first=G.|coauthors='et al.''|year=2009|title=Non-Gaussian Signatures in the five-year WMAP data as identified with isotropic scaling indices|class=astro-ph.CO|eprint=0905.2854}}</ref><ref name="arXiv:0802.3229">{{cite arxiv|last=Schild|first=R. E.|last2=Gibson|first2=C. H.|year=2008|title=Goodness in the Axis of Evil|class=astro-ph|eprint=0802.3229}}</ref><ref name="arXiv:astro-ph/0511666">{{cite arxiv|last=Bernui|first=A.|coauthors=''et al.''|year=2005|title=Mapping the large-scale anisotropy in the WMAP data|class=astro-ph|eprint=astro-ph/0511666}}</ref><ref name="arXiv:astro-ph/0503213">{{cite arxiv|last=Jaffe|first=T.R.|coauthors=''et al.''|year=2005|title=Evidence of vorticity and shear at large angular scales in the WMAP data: a violation of cosmological isotropy?|class=astro-ph|eprint=astro-ph/0503213}}</ref> The most longstanding of these is the low-''l'' multipole controversy. Even in the COBE map, it was observed that the [[quadrupole]] (''l''=2 spherical harmonic) has a low amplitude compared to the predictions of the big bang. Some observers have pointed out that the anisotropies in the WMAP data did not appear to be consistent with the big bang picture. In particular, the quadrupole and octupole (''l''=3) modes appear to have an unexplained alignment with each other and with the [[plane of the ecliptic|ecliptic plane]]<ref>
{{cite journal|last=de Oliveira-Costa |first=A. |coauthors=''et al.''|year=2004|title=The significance of the largest scale CMB fluctuations in WMAP|journal=[[Physical Review D]]|volume=69|pages=063516|doi=10.1103/PhysRevD.69.063516|id={{arxiv|astro-ph/0307282}}}}</ref><ref>{{cite journal|last=Schwarz|first=D. J.|coauthors=''et al,''|year=2004|title=Is the low-''l'' microwave background cosmic?|journal=[[Physical Review Letters]]|volume=93|pages=221301|doi=10.1103/PhysRevLett.93.221301|id={{arxiv|astro-ph/0403353}}}}</ref><ref>
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