Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion

Large-scale structure (LSS) surveys are a powerful probe of primordial non-Gaussianity (PNG) and, by extension, inflation. However, extracting PNG from small-scale LSS data is challenging due to the significant non-Gaussianities generated by non-linear gravitational evolution and complex astrophysical processes. In this talk, I will discuss recent progress towards constraining PNG in the non-linear regime using the LSS consistency relations — non-perturbative statements (soft theorems) about LSS correlators derived from the symmetries of the LSS equations of motion. Using the separate universe formalism, I will derive non-perturbative models for the squeezed matter bispectrum and collapsed matter trispectrum in the presence of both local PNG and more general “Cosmological Collider” signals from inflationary massive particle exchange. I will validate these models deep into the non-linear regime (k~2 h/Mpc at z=0) using N-body simulations. Finally, I will discuss the non-linear evolution of oscillatory features in the squeezed bispectrum, showing that wiggly features in the bispectrum are significantly damped by gravitational evolution. This damping is well-described by separate universe simulations and can be largely undone using reconstruction techniques originally developed for baryon acoustic oscillation (BAO) analysis. These results can significantly extend the range of scales accessible to PNG searches, enhancing our ability to probe the physics of the early Universe.