return to the ECR seminar schedule
CMB studies of primordial features and early universe physics
Speaker
Wuhyun Sohn KASI (Dajeon, South Korea)
Abstract
While the simplest model of inflation is consistent with current observations, numerous well-motivated models of the early universe predict some oscillations in the primordial power spectrum and/or bispectrum. We present our recent works on studying early universe physics using CMB data with a focus on primordial features. First, we search for hints of features in the primordial power spectrum via a free-form reconstruction equipped with a regularisation term inspired by image analysis techniques. Its statistical significance is then tested using mock data. We also explore other methods such as Genetic Algorithms and Gaussian Processes to search for localised features and test the consistency of the CMB datasets used. Second, we present our publicly available code CMB-BEST for getting Planck constraints on primordial non-Gaussianity for any given bispectrum shape. The code is applied to study some highly oscillatory bispectrum templates that were previously out of reach, to put constraints on a model of Degenerate High Order Scalar-Tensor (DHOST) theory, and to allow joint analysis in combination with power spectrum likelihood. We summarise that, while there is no concrete evidence of primordial features, many such models remain viable and will be constrained with upcoming CMB surveys.
Date and Time
September 5 2023 11am KST (= 2am UTC) Zoom link (active once the seminar starts)