Data di Pubblicazione:
2014
Abstract:
The two fundamental assumptions of the standard cosmological model -
that the initial fluctuations are statistically isotropic and Gaussian -
are rigorously tested using maps of the cosmic microwave background
(CMB) anisotropy from the Planck satellite. The detailed results are
based on studies of four independent estimates of the CMB that are
compared to simulations using a fiducial LambdaCDM model and
incorporating essential aspects of the Planck measurement process.
Deviations from isotropy have been found and demonstrated to be robust
against component separation algorithm, mask choice, and frequency
dependence. Many of these anomalies were previously observed in the WMAP
data, and are now confirmed at similar levels of significance (about
3sigma). However, we find little evidence of non-Gaussianity, with the
exception of a few statistical signatures that seem to be associated
with specific anomalies. In particular, we find that the
quadrupole-octopole alignment is also connected to a low observed
variance in the CMB signal. A power asymmetry is now found to persist on
scales corresponding to about l = 600 and can be described in the
low-l regime by a phenomenological dipole modulation model. However,
any primordial power asymmetry is strongly scale-dependent and does not
extend toarbitrarily small angular scales. Finally, it is plausible that
some of these features may be reflected in the angular power spectrum of
the data, which shows a deficit of power on similar scales. Indeed, when
the power spectra of two hemispheres defined by a preferred direction
are considered separately, one shows evidence of a deficit in power,
while its opposite contains oscillations between odd and even modes that
may be related to the parity violation and phase correlations also
detected in the data. Although these analyses represent a step forward
in building an understanding of the anomalies, a satisfactory
explanation based on physically motivated models is still lacking.
that the initial fluctuations are statistically isotropic and Gaussian -
are rigorously tested using maps of the cosmic microwave background
(CMB) anisotropy from the Planck satellite. The detailed results are
based on studies of four independent estimates of the CMB that are
compared to simulations using a fiducial LambdaCDM model and
incorporating essential aspects of the Planck measurement process.
Deviations from isotropy have been found and demonstrated to be robust
against component separation algorithm, mask choice, and frequency
dependence. Many of these anomalies were previously observed in the WMAP
data, and are now confirmed at similar levels of significance (about
3sigma). However, we find little evidence of non-Gaussianity, with the
exception of a few statistical signatures that seem to be associated
with specific anomalies. In particular, we find that the
quadrupole-octopole alignment is also connected to a low observed
variance in the CMB signal. A power asymmetry is now found to persist on
scales corresponding to about l = 600 and can be described in the
low-l regime by a phenomenological dipole modulation model. However,
any primordial power asymmetry is strongly scale-dependent and does not
extend toarbitrarily small angular scales. Finally, it is plausible that
some of these features may be reflected in the angular power spectrum of
the data, which shows a deficit of power on similar scales. Indeed, when
the power spectra of two hemispheres defined by a preferred direction
are considered separately, one shows evidence of a deficit in power,
while its opposite contains oscillations between odd and even modes that
may be related to the parity violation and phase correlations also
detected in the data. Although these analyses represent a step forward
in building an understanding of the anomalies, a satisfactory
explanation based on physically motivated models is still lacking.
Tipologia CRIS:
1.1 Articolo in rivista
Keywords:
cosmic background radiation; cosmology: observations; cosmology: miscellaneous
Elenco autori:
P., Collaboration; P. A., R.; N., Aghanim; C., Armitage Caplan; M., Arnaud; M., Ashdown; F., Atrio Barandela; J., Aumont; C., Baccigalupi; A. J., Banday; R. B., Barreiro; J. G., Bartlett; N., Bartolo; E., Battaner; R., Battye; K., Benabed; A., Beno�t; A., Benoit L�vy; J., Bernard; M., Bersanelli; P., Bielewicz; J., Bobin; J. J., Bock; A., Bonaldi; L., Bonavera; J. R., Bond; J., Borrill; F. R., Bouchet; M., Bridges; M., Bucher; C., Burigana; R. C., Butler; J., Cardoso; A., Catalano; A., Challinor; A., Chamballu; R., Chary; H. C., Chiang; L., Chiang; P. R., Christensen; S., Church; D. L., Clements; S., Colombi; L. P., L.; F., Couchot; A., Coulais; B. P., Crill; M., Cruz; A., Curto; F., Cuttaia; L., Danese; R. D., Davies; R. J., Davis; P. d., Bernardis; A. d., Rosa; G. d., Zotti; J., Delabrouille; J., Delouis; F., D�sert; J. M., Diego; H., Dole; S., Donzelli; O., Dor�; M., Douspis; A., Ducout; X., Dupac; G., Efstathiou; F., Elsner; T. A., En�lin; H. K., Eriksen; Y., Fantaye; J., Fergusson; F., Finelli; O., Forni; M., Frailis; E., Franceschi; M., Frommert; S., Galeotta; K., Ganga; M., Giard; G., Giardino; Y., Giraud H�raud; J., Gonz�lez Nuevo; K. M., G�rski; S., Gratton; A., Gregorio; A., Gruppuso; F. K., Hansen; M., Hansen; D., Hanson; D. L., Harrison; G., Helou; S., Henrot Versill�; C., Hern�ndez Monteagudo; D., Herranz; S. R., Hildebrandt; E., Hivon; M., Hobson; W. A., Holmes; A., Hornstrup; W., Hovest; K. M., Huffenberger; A. H., Jaffe; T. R., Jaffe; W. C., Jones; M., Juvela; E., Keih�nen; R., Keskitalo; J., Kim; T. S., Kisner; J., Knoche; L., Knox; M., Kunz; H., Kurki Suonio; G., Lagache; A., L�hteenm�ki; J., Lamarre; A., Lasenby; R. J., Laureijs; C. R., Lawrence; J. P., Leahy; R., Leonardi; C., Leroy; J., Lesgourgues; M., Liguori; P. B., Lilje; M., Linden V�rnle; M., L�pez Caniego; P. M., Lubin; J. F., Mac�as P�rez; B., Maffei; D., Maino; N., Mandolesi; A., Mangilli; D., Marinucci; M., Maris; D. J., Marshall; P. G., Martin; E., Mart�nez Gonz�lez; S., Masi; M., Massardi; S., Matarrese; F., Matthai; P., Mazzotta; J. D., Mcewen; P. R., Meinhold; A., Melchiorri; L., Mendes; A., Mennella; M., Migliaccio; K., Mikkelsen; S., Mitra; M., Miville Desch�nes; D., Molinari; A., Moneti; L., Montier; G., Morgante; D., Mortlock; A., Moss; D., Munshi; J. A., Murphy; P., Naselsky; F., Nati; P., Natoli; C. B., Netterfield; H. U., N�rgaard Nielsen; F., Noviello; D., Novikov; I., Novikov; S., Osborne; C. A., Oxborrow; F., Paci; L., Pagano; F., Pajot; D., Paoletti; F., Pasian; G., Patanchon; H. V., Peiris; O., Perdereau; L., Perotto; F., Perrotta; F., Piacentini; M., Piat; E., Pierpaoli; D., Pietrobon; S., Plaszczynski; D., Pogosyan; E., Pointecouteau; G., Polenta; N., Ponthieu; L., Popa; T., Poutanen; G. W., Pratt; G., Pr�zeau; S., Prunet; J., Puget; J. P., Rachen; B., Racine; C., R�th; R., Rebolo; M., Reinecke; M., Remazeilles; C., Renault; A., Renzi; S., Ricciardi; T., Riller; I., Ristorcelli; G., Rocha; C., Rosset; A., Rotti; G., Roudier; Mart�n, J. A. Rubi�o.; B., Ruiz Granados; B., Rusholme; M., Sandri; D., Santos; G., Savini; D., Scott; M. D., Seiffert; E. P., S.; T., Souradeep; L. D., Spencer; J., Starck; V., Stolyarov; R., Stompor; R., Sudiwala; F., Sureau; P., Sutter; D., Sutton; A., Suur Uski; J., Sygnet; J. A., Tauber; D., Tavagnacco; Terenzi, Luca; L., Toffolatti; M., Tomasi; M., Tristram; M., Tucci; J., Tuovinen; M., T�rler; L., Valenziano; J., Valiviita; B. V., Tent; J., Varis; P., Vielva; F., Villa; N., Vittorio; L. A., Wade; B. D., Wandelt; I. K., Wehus; M., White; A., Wilkinson; D., Yvon; A., Zacchei; A., Zonca
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