2015/11/30 by Christian T. Byrnes, Donough Regan, David Seery +2 · 1 citation
Physics and Astronomy · #Amplitude #Asymmetry #Bispectrum #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Function (biology) #Galaxies: Formation, Evolution, Phenomena #Inflation (cosmology) #Non-Gaussianity #Particle physics theoretical and experimental studies #astro-ph.CO #hep-th
paper · pdf · doi:10.1088/1475-7516/2016/06/025
published as JCAP 1606 (2016) 025 · 38 pages plus references, 7 figures. v2: Minor changes to match version published in JCAP. This is an author-created, un-copyedited version of an article published in JCAP. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/1475-7516/2016/06/025
openalex publication_date 2016/06/10 · arxiv created 2016/06/24 · openalex created_date 2016/06/24 · arxiv updated 2016/06/27 · openalex updated_date 2026/08/06
If the primordial bispectrum is sufficiently large then the CMB hemispherical power asymmetry may be explained by a large-scale mode of exceptional amplitude which perturbs the ζ two-point function. We extend previous calculations, which were restricted to one- or two-source scenarios, by providing a method to compute the response of the two-point function in any model yielding a `local-like' bispectrum. In general, this shows that it is not the reduced bispectrum f NL ( k 1 , k 2 , k 3 ) which sources the amplitude and scale-dependence of the mode coupling but rather a combination of `response functions'. We discuss why it is difficult to construct successful scenarios and enumerate the fine-tunings which seem to be required. Finally, we exhibit a concrete model which can be contrived to match the observational constraints and show that to a Planck-like experiment it would appear to have | NL local | ∼ | NL equi | ∼ | NL ortho | ≲ 1. Therefore, contrary to previous analyses, we conclude that it is possible to generate the asymmetry while respecting observational constraints on the bispectrum and low-ℓ multipoles even without tuning our location on the long-wavelength mode.