Non-Gaussian Shape Recognition

Abstract

A detection of primordial non-Gaussianity could transform our understanding of the fundamental theory of inflation. The precision promised by upcoming CMB and large-scale structure surveys raises a natural question: if a detection given a particular template is made, what does this truly tell us about the underlying theory? In this paper we present a systematic way to constrain a wide range of non-Gaussian shapes, including general single and multi-field models and models with excited initial states. We present a separable, divergent basis able to recreate many shapes in the literature to high accuracy with between three and seven basis functions. The basis allows shapes to be grouped into broad "template classes", satisfying theoretically-relevant priors on their divergence properties in the squeezed limit. We forecast how well a Planck-like CMB survey could not only detect a general non-Gaussian signal but discern more about its shape, using existing templates and new ones we propose. This approach offers an opportunity to tie together minimal theoretical priors with observational constraints on the shape in general, and in the squeezed limit, to gain a deeper insight into what drove inflation.

37 pages, 7 figures, 5 tables. Matches the JCAP accepted version

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Cited by in corpus (12)

• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Galaxy redshift-space bispectrum: the Importance of Being Anisotropic
• Capturing Non-Gaussianity of the Large-Scale Structure with Weighted Skew-Spectra
• An optimal estimator for resonance bispectra in the CMB
• Optimal CMB estimators for bispectra from excited states
• Why does the effective field theory of inflation work?
• Non-Gaussian Shape Discrimination with Spectroscopic Galaxy Surveys
• Constraining Galileon Inflation
• Looking for non-Gaussianity in all the right places: A new basis for non-separable bispectra
• Optimal bispectrum constraints on single-field models of inflation
• Modes of the Dark Ages 21cm field accessible to a lunar radio interferometer
• On the space of non-Gaussian fields with single-clock bispectra