A New Window on Primordial non-Gaussianity

2012/01/31 by Enrico Pajer, Matias Zaldarriaga · 1 citation
Physics and Astronomy · #astro-ph.CO #astro-ph.GA #gr-qc #hep-ph #hep-th

paper · pdf · doi:10.1103/physrevlett.109.021302

5 pages, one figure. v2: added clarifying comments and references, fixed typos

arxiv created 2012/09/10 · arxiv updated 2013/05/29

Abstract

We know very little about primordial curvature perturbations on scales smaller than about a Mpc. Measurements of the mu-type distortion of the CMB spectrum provide the unique opportunity to probe these scales over the unexplored range from 50 to 10⁴ Mpc^-1. This is a very clean probe, in that it relies only on well-understood linear evolution. We point out that correlations between mu-distortion and temperature anisotropies can be used to test Gaussianity at these very small scales. In particular the mu-T cross correlation is proportional to the very squeezed limit of the primordial bispectrum and hence measures fNL^loc, while mu-mu is proportional to the primordial trispectrum and measures tauNL. We present a Fisher matrix forecast of the observational constraints.

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