Prospects for constraining the shape of non-Gaussianity with the scale-dependent bias

Jorge Noreña, Licia Verde, Gabriela Barenboim, Cristian Bosch

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45 Scopus citations


We consider whether the non-Gaussian scale-dependent halo bias can be used not only to constrain the local form of non-Gaussianity but also to distinguish among different shapes. In particular, we ask whether it can constrain the behavior of the primordial three-point function in the squeezed limit where one of the momenta is much smaller than the other two. This is potentially interesting since the observation of a three-point function with a squeezed limit that does not go like the local nor equilateral templates would be a signal of non-trivial dynamics during inflation. To this end we use the quasi-single field inflation model of Chen & Wang [1, 2] as a representative two-parameter model, where one parameter governs the amplitude of non-Gaussianity and the other the shape. We also perform a model-independent analysis by parametrizing the scale-dependent bias as a power-law on large scales, where the power is to be constrained from observations. We find that proposed large-scale structure surveys (with characteristics similar to the dark energy task force stage IV surveys) have the potential to distinguish among the squeezed limit behavior of different bispectrum shapes for a wide range of fiducial model parameters. Thus the halo bias can help discriminate between different models of inflation.

Original languageEnglish
Article number019
JournalJournal of Cosmology and Astroparticle Physics
Issue number8
StatePublished - Aug 2012
Externally publishedYes


  • Cosmological parameters from LSS
  • Inflation
  • Redshift surveys


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