Planck 2015 results XVII. Constraints on primordial non-Gaussianity
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
The Planck full mission cosmic microwave background (CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity (NG). Using three classes of optimal bispectrum estimators – separable template-fitting (KSW), binned, and modal – we obtain consistent values for the primordial local, equilateral, and orthogonal bispectrum amplitudes, quoting as our final result from temperature alone ƒlocalNL = 2.5 ± 5.7, ƒequilNL= -16 ± 70, , and ƒorthoNL = -34 ± 32 (68% CL, statistical). Combining temperature and polarization data we obtain ƒlocalNL = 0.8 ± 5.0, ƒequilNL= -4 ± 43, and ƒorthoNL = -26 ± 21 (68% CL, statistical). The results are based on comprehensive cross-validation of these estimators on Gaussian and non-Gaussian simulations, are stable across component separation techniques, pass an extensive suite of tests, and are consistent with estimators based on measuring the Minkowski functionals of the CMB. The effect of time-domain de-glitching systematics on the bispectrum is negligible. In spite of these test outcomes we conservatively label the results including polarization data as preliminary, owing to a known mismatch of the noise model in simulations and the data. Beyond estimates of individual shape amplitudes, we present model-independent, three-dimensional reconstructions of the Planck CMB bispectrum and derive constraints on early universe scenarios that generate primordial NG, including general single-field models of inflation, axion inflation, initial state modifications, models producing parity-violating tensor bispectra, and directionally dependent vector models. We present a wide survey of scale-dependent feature and resonance models, accounting for the “look elsewhere” effect in estimating the statistical significance of features. We also look for isocurvature NG, and find no signal, but we obtain constraints that improve significantly with the inclusion of polarization. The primordial trispectrum amplitude in the local model is constrained to be localNL = (-0.9 ± 7.7 ) X 104(68% CL statistical), and we perform an analysis of trispectrum shapes beyond the local case. The global picture that emerges is one of consistency with the premises of the ΛCDM cosmology, namely that the structure we observe today was sourced by adiabatic, passive, Gaussian, and primordial seed perturbations.
Date Issued
2016-10-01
Date Acceptance
2016-01-27
Citation
Astronomy and Astrophysics: a European journal, 2016, 594 (10)
ISSN
0004-6361
Publisher
EDP Sciences
Journal / Book Title
Astronomy and Astrophysics: a European journal
Volume
594
Issue
10
Copyright Statement
© 2016 ESO.
Sponsor
Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
Imperial College Trust
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000385832200016&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
ST-N000838
ST/N000838/1
N/A
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
cosmic background radiation
cosmology: observations
cosmology: theory
early Universe
inflation
methods: data analysis
INFRARED BACKGROUND ANISOTROPIES
3-POINT CORRELATION-FUNCTION
PROBE WMAP OBSERVATIONS
LARGE-SCALE STRUCTURE
MINKOWSKI FUNCTIONALS
POLARIZATION ANISOTROPIES
FAST ESTIMATOR
POINT SOURCES
CMB
TEMPERATURE
astro-ph.CO
astro-ph.CO
0201 Astronomical and Space Sciences
Astronomy & Astrophysics
Publication Status
Published
Article Number
ARTN A17
Date Publish Online
2016-09-20