Primordial Physics in the Nonlinear Universe: mapping cosmological collider models to weak-lensing observables

Abstract: Primordial non-Gaussianities (PNGs) are features in the initial density field that provide a window into the nonlinear dynamics of particles during the inflationary epoch. Among them, a distinctive set of signatures from "cosmological collider physics" originates through interactions of the inflaton with heavy particles active at high energies. The amplitude and form of these signatures depend on the strength and nature of the interactions. The corresponding features in large-scale structure have been studied predominantly through the use of perturbation theory, restricted to the linear regime of the density field. In this work, we implement a method for running cosmological simulations with arbitrary bispectra signals in their initial density field, and produce a simulation suite of over thirty PNG-generating templates, resolving the corresponding collider signatures in the strongly nonlinear regime of the density field. We detail the signals in a variety of late-time measurements -- the matter power spectra, matter bispectra, the halo abundance, and halo bias. We then forecast the potential constraints on the signal amplitudes using weak lensing measurements from the Year-10 dataset of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). The second and third moments of the lensing convergence field produce constraints that are competitive and complementary to those from the Cosmic Microwave Background. The data products are publicly released as part of the Ulagam simulation suite. Our initial conditions generator is also publicly available at https://github.com/DhayaaAnbajagane/Aarambam.