Constraining primordial non-Gaussianity (PNG) offers a unique lens into the physics of the early Universe, probing energy scales far beyond the reach of terrestrial experiments. The large-scale structure (LSS) of the Universe encodes valuable information, and ongoing galaxy surveys, such as DESI, have the potential to greatly improve current constraints. This thesis investigates how PNG affects LSS observables and how simulations can be used to characterize these effects. First, I introduce a novel framework to generate non-Gaussian initial conditions for cosmological simulations, enabling studies of non-standard models. I then provide examples of applications to oscillatory and scale-dependent scenarios, outlining their imprint on nonlinear clustering. Finally, I focus on local PNG, which induces a sharp scale-dependent feature in the galaxy power spectrum—one of the most promising avenues for testing multi-field inflation. Showing its dependence on dark matter halo assembly history, I will propose observational proxies calibrated on hydrodynamical simulations that link this effect to galaxy properties. Applied to quasar samples relevant for DESI, these results provide priors that strengthen upcoming constraints.

Tribunal:

President: Dr. Héctor Gil-Marín

Secretari: Dr. Santiago Javier Avila Pérez

Vocal: Dr. Matteo Viel

Suplents:

Dr. Marc Manera Miret

Dr. Raul Jimenez

Directora: Dra. Licia Verde

Tutor: Dr. Alberto Manrique Oliva