Résumé / Abstract Journal-club_Galaxies

Séminaire/Seminar Galaxies

« Galaxy formation and primordial non-Gaussianities »

Clément Stahl
Obs. Astron. Strasbourg (Strasbourg, France)

In this talk, I will show you my investigation of the effect of significant small-scale primordial non-Gaussianity on structure formation and the galaxy formation process. Specifically, I explored four different types of non-Gaussianities: positive and negative skeweness and kurtosis. Generically, I find a distinct and potentially detectable feature in the matter power spectrum around the non-linear scale. The feature might have interesting consequences for the S8 tension. I then show in particular that a positively skewed distribution with fNL of the order of 1000 at these scales, implies that typical galaxy-sized halos reach half of their present-day mass at an earlier stage and have a quieter merging history at z < 3 than in the Gaussian case. Their environment between 0.5 and 4 viri al radii at z = 0 is less dense than in the Gaussian case and may impact the universality of the NFW profile. This quieter history and less dense environment has potentially interesting consequences in terms of the formation of bulges and bars. In particular, I show that all feedback prescriptions being otherwise identical, simulations with a positively skewed distribution , hence forming galaxies a bit later than in vanilla ?CDM, allow to form simulated galaxies with more disky kinematics than in the vanilla case. Therefore, such small-scale primordial non-Gaussianities could potentially help alleviate, simultaneously, tensions in cosmology and galaxy formation. These hydrodynamical simulations on small scales will need to be complemented with larger box "zoom-in" simulations with scale-dependent non-Gaussianities, to statistically confirm these trends and explore their observational consequences in further detail.
jeudi 18 janvier 2024 - 11:30
Salle des séminaires Évry Schatzman
Institut d'Astrophysique de Paris
Page web du séminaire / Seminar's webpage