Looking for non-Gaussianity in all the right places: A new basis for nonseparable bispectra

Byun, Joyce; Agarwal, Nishant; Bean, Rachel; Holman, R.

doi:10.1103/physrevd.91.123518

Cited by 8 publications

(5 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are a number of existing methods for building a basis functions for Q s , e.g. [77][78][79]. Instead, let us consider an ansatz given by The terms in the square brackets in Eq.…”

Section: B Separable Templatesmentioning

confidence: 99%

Capturing non-Gaussianity of the large-scale structure with weighted skew-spectra

Dizgah

Lee

Schmittfull

et al. 2020

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

The forthcoming generation of wide-field galaxy surveys will probe larger volumes and galaxy densities, thus allowing for a much larger signal-to-noise ratio for higher-order clustering statistics, in particular the galaxy bispectrum. Extracting this information, however, is more challenging than using the power spectrum due to more complex theoretical modeling, as well as significant computational cost of evaluating the bispectrum signal and the error budget. To overcome these challenges, several proxy statistics have been proposed in the literature, which partially or fully capture the information in the bispectrum, while being computationally less expensive than the bispectrum. One such statistics are weighted skew-spectra, which are cross-spectra of the density field and appropriately weighted quadratic fields. Using Fisher forecasts, we show that the information in these skew-spectra is equivalent to that in the bispectrum for parameters that appear as amplitudes in the bispectrum model, such as galaxy bias parameters or the amplitude of primordial non-Gaussianity. We consider three shapes of the primordial bispectrum: local, equilateral and that due to massive particles with spin two during inflation. To obtain constraints that match those from a measurement of the full bispectrum, we find that it is crucial to account for the full covariance matrix of the skew-spectra.

show abstract

“…There are a number of existing methods for building a basis functions for Q s , e.g. [77][78][79]. Instead, let us consider an ansatz given by The terms in the square brackets in Eq.…”

Section: B Separable Templatesmentioning

confidence: 99%

Capturing non-Gaussianity of the large-scale structure with weighted skew-spectra

Dizgah

Lee

Schmittfull

et al. 2020

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…For sensitivity to oscillatory signatures in the bispectrum (as is expected in resonance models), Meerburg proposed a separable Fourier mode basis [376] lxxii . More recently, Byun et al proposed a basis of localized piecewise spline functions tailored towards non-separable bispectra [377]. Given a particular choice, one can then make a modal expansion of a given shape function as…”

Section: Higher Order Correlatorsmentioning

confidence: 99%

Features and New Physical Scales in Primordial Observables: Theory and Observation

Chluba,

Hamann,

Patil

2015

Preprint

View full text Add to dashboard Cite

All cosmological observations to date are consistent with adiabatic, Gaussian and nearly scale invariant initial conditions. These findings provide strong evidence for a particular symmetry breaking pattern in the very early universe (with a close to vanishing order parameter, ), widely accepted as conforming to the predictions of the simplest realizations of the inflationary paradigm. However, given that our observations are only privy to perturbations, in inferring something about the background that gave rise to them, it should be clear that many different underlying constructions project onto the same set of cosmological observables. Features in the primordial correlation functions, if present, would offer a unique and discriminating window onto the parent theory in which the mechanism that generated the initial conditions is embedded. In certain contexts, simple linear response theory allows us to infer new characteristic scales from the presence of features that can break the aforementioned degeneracies among different background models, and in some cases can even offer a limited spectroscopy of the heavier degrees of freedom that couple to the inflaton. In this review, we offer a pedagogical survey of the diverse, theoretically well grounded mechanisms which can imprint features into primordial correlation functions in addition to reviewing the techniques one can employ to probe observations. These observations include cosmic microwave background anisotropies and spectral distortions as well as the matter two and three point functions as inferred from large-scale structure and potentially, 21 cm surveys.xiii Conversely, any 'sharp' features in the inflaton potential or sudden drops in cs (defined as those for whose derivatives become comparable to the cut-off of the theory) are unlikely to be radiatively stable, as quantum corrections tend to smear these out in field space or in time, respectively. xiv This is due to the same volume vs surface area gain in the number of modes available as noted in footnote v.

show abstract

Section: Higher Order Correlatorsmentioning

confidence: 99%

Features and new physical scales in primordial observables: Theory and observation

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

208

233

View full text Add to dashboard Cite

June 22, 20152 All cosmological observations to date are consistent with adiabatic, Gaussian and nearly scale invariant initial conditions. These findings provide strong evidence for a particular symmetry breaking pattern in the very early universe (with a close to vanishing order parameter, ), widely accepted as conforming to the predictions of the simplest realizations of the inflationary paradigm. However, given that our observations are only privy to perturbations, in inferring something about the background that gave rise to them, it should be clear that many different underlying constructions project onto the same set of cosmological observables. Features in the primordial correlation functions, if present, would offer a unique and discriminating window onto the parent theory in which the mechanism that generated the initial conditions is embedded. In certain contexts, simple linear response theory allows us to infer new characteristic scales from the presence of features that can break the aforementioned degeneracies among different background models, and in some cases can even offer a limited spectroscopy of the heavier degrees of freedom that couple to the inflaton. In this review, we offer a pedagogical survey of the diverse, theoretically well grounded mechanisms which can imprint features into primordial correlation functions in addition to reviewing the techniques one can employ to probe observations. These observations include cosmic microwave background anisotropies and spectral distortions as well as the matter two and three point functions as inferred from large-scale structure and potentially, 21 cm surveys.

show abstract

Looking for non-Gaussianity in all the right places: A new basis for nonseparable bispectra

Cited by 8 publications

References 59 publications

Capturing non-Gaussianity of the large-scale structure with weighted skew-spectra

Capturing non-Gaussianity of the large-scale structure with weighted skew-spectra

Features and New Physical Scales in Primordial Observables: Theory and Observation

Features and new physical scales in primordial observables: Theory and observation

Contact Info

Product

Resources

About