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Journal Articles Physical Review D Year : 2015

Optimal estimator for resonance bispectra in the CMB


We propose an (optimal) estimator for a CMB bispectrum containing logarithmically spaced oscillations. There is tremendous theoretical interest in such bispectra, and they are predicted by a plethora of models, including axion monodromy models of inflation and initial state modifications. The number of resolved logarithmical oscillations in the bispectrum is limited due to the discrete resolution of the multipole bispectrum. We derive a simple relation between the maximum number of resolved oscillations and the frequency. We investigate several ways to factorize the primordial bispectrum, and conclude that a one-dimensional expansion in the sum of the momenta ∑ki=kt is the most efficient and flexible approach. We compare the expansion to the exact result in multipole space and show for ωeff=100 that O (1 03) modes are sufficient for an accurate reconstruction. We compute the expected σfNL and find that within an effective field theory (EFT) the overall signal to noise scales as S /N ∝ω3 /2. Using only the temperature data we find S /N ∼O (1 - 1 02) for the frequency domain set by the EFT.
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insu-03644760 , version 1 (29-04-2022)



Moritz Münchmeyer, P. Daniel Meerburg, Benjamin D. Wandelt. Optimal estimator for resonance bispectra in the CMB. Physical Review D, 2015, 91, ⟨10.1103/PhysRevD.91.043534⟩. ⟨insu-03644760⟩
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