Abstract
Many inflation models predict that primordial density perturbations have a nonzero three-point correlation function, or bispectrum in Fourier space. Of the several possibilities for this bispectrum, the most common is the local-model bispectrum, which can be described as a spatial modulation of the small-scale (large-wavenumber) power spectrum by long-wavelength density fluctuations. While the local model predicts this spatial modulation to be scale independent, many variants have some scale dependence. Here we note that this scale dependence can be probed with measurements of frequency-spectrum distortions in the cosmic microwave background (CMB), in particular, highlighting Compton- distortions. Dissipation of primordial perturbations with wavenumbers gives rise to chemical-potential () distortions, while dissipation of those with wavenumbers gives rise to Compton- distortions. With local-model non-Gaussianity, the distortions induced by this dissipation can be distinguished from those due to other sources via their cross correlation with the CMB temperature . We show that the relative strengths of the and correlations thus probe the scale dependence of non-Gaussianity and estimate the magnitude of possible signals relative to the sensitivities of future experiments. We discuss the complementarity of these measurements with other probes of squeezed-limit non-Gaussianity.
- Received 5 April 2015
DOI:https://doi.org/10.1103/PhysRevD.91.123531
© 2015 American Physical Society