Primordial non-Gaussianity without tails -- how to measure fNL with the bulk of the density PDF

Understand

We investigate the possibility to detect primordial non-Gaussianity by analysing the bulk of the probability distribution function (PDF) of late-time cosmic density fluctuations.

• For this purpose we devise a new method to predict the impact of general non-Gaussian initial conditions on the late-time density PDF.
• At redshift $z=1$ and for a smoothing scale of 30Mpc/$h$ our predictions agree with the high-resolution Quijote N-body simulations to $\sim 0.2\%$ precision.
• This is within cosmic variance of a $\sim 100(\mathrm{Gpc}/h)^3$ survey volume.