The observed galaxy bispectrum from single-field inflation in the squeezed limit

Kazuya Koyama, Obinna Umeh, Roy Maartens, Daniele Bertacca

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Abstract

Using the consistency relation in Fourier space, we derive the observed galaxy bispectrum from single-field inflation in the squeezed limit, in which one of the three modes has a wavelength much longer than the other two. This provides a non-trivial check of the full computation of the bispectrum based on second-order cosmological perturbation theory in this limit. We show that gauge modes need to be carefully removed in the second-order cosmological perturbations in order to calculate the observed galaxy bispectrum in the squeezed limit. We then give an estimate of the effective non-Gaussianity due to general relativistic lightcone effects that could mimic a primordial non-Gaussian signal.
Original languageEnglish
Article number050
Number of pages20
JournalJournal of Cosmology and Astroparticle Physics
Volume2018
Issue number07
DOIs
Publication statusPublished - 23 Jul 2018

Keywords

  • astro-ph.CO
  • gr-qc
  • hep-th
  • RCUK
  • STFC
  • ST/N000668/1

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