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6–8 May 2024
Building 50
US/Pacific timezone

Constraining local primordial non-Gaussianity using the large-scale modulation of small-scale statistics

7 May 2024, 14:10
10m
Auditorium (Building 50)

Auditorium

Building 50

Speaker

Dr Utkarsh Giri (University of Wisconsin-Madison)

Description

We implement a novel formalism to constrain primordial non-Gaussianity of the local type from the large-scale modulation of the small-scale power spectrum. Our approach combines information about primordial non-Gaussianity contained in the squeezed bispectrum and the collapsed trispectrum of large-scale structure together in a computationally amenable and consistent way, while avoiding the need to model complicated covariances of higher N-point functions. We perform a simulation based study and explore using both matter field and halo catalogues from the Quijote simulations. We find that higher N-point functions of the matter field can provide strong constraints local on non-Gaussianity parameter fNL, but higher N-point functions of the halo field, at the halo density of Quijote, only marginally improve constraints from the two-point function. In subsequent work, we take this idea further and train a neural network to locally estimate the amplitude of linear fluctuation σ8 from matter density field and correlate these local estimates with the large-scale density field. We apply our method to N-body simulations, and show that σ(fNL) is 5.5 times better than the constraint obtained from a standard halo-based approach. We show that our method has the same robustness property as large-scale halo bias: baryonic physics can change the normalization of the estimated fNL, but cannot change whether fNL is detected.

Authors

Dr Utkarsh Giri (University of Wisconsin-Madison) Prof. Moritz Muenchmeyer (University of Wisconsin-Madison) Prof. Kendrick Smith (Perimeter Institute)

Presentation materials