- Nov. 20, 2023, 2:00 pm US/Central
- The Dark Side WH6W
- Utkarsh Giri, U Wisconsin, Madison
- Host: Dylan Temples, dtemples@fnal.gov
Abstract: Searching for signatures of non-Gaussianity in primordial fluctuations is one of the foremost quests in modern cosmology. A successful detection will rule out single-field inflation models. In my talk, I will present a novel, non-perturbative formalism to constrain the local type primordial non-Gaussianity (PNG) parameter f_NL, tapping into information from deeply non-linear scales. We transform density field into an auxiliary field, \pi , which is an estimate of local small-scale power spectra in space. The PNG signature in the \pi field appears as a unique 1/k2 bias with respect to the density field. The auto-spectrum and cross-spectrum of the field with the large-scale density combines information about PNG contained in the soft-limits of higher N-point functions in a computationally amenable and consistent way, while avoiding the need to model complicated covariances of these higher N-point functions. We subsequently generalize our work and train a neural network to estimate local power with much higher precision. We apply our method to simulations and show that constraints on f_NL are 5.5 times better than those obtained from a standard matter+halo based analysis. Our method is robust to systematics as symmetry arguments imply that the signature cannot be faked by any other physics.