Browsing by Subject "galaxies: halos"

I use hydrodynamic cosmological N-body simulations to study the effect that a secondary period of inflation, driven by a spectator field, would have on the Local Group substructures. Simulations of the Local Group have been widely adopted for studying the nonlinear structure formation on small scales. This is essentially because detailed observations of faint dwarf galaxies are mostly limited to within the Local Group and its immediate surroundings. In particular, the ∼ 100 dwarf galaxies, discovered out to a radius of 3 Mpc from the Sun, constitute a sample that has the potential to discriminate between different cosmological models on small scales, when compared to simulations. The two-period inflaton-curvaton inflation model is one such example, since it gives rise to a small-scale cut-off in the ΛCDM primordial power spectrum, compared to the power spectrum of the ΛCDM model with single field power-law inflation. I investigate the substructures that form in a simulated analogue of the Local Group, with initial conditions that incorporate such a modified power spectrum. The most striking deviation, from the standard power-law inflation, is the reduction of the total number of subhalos, with v_max > 10 km/s, by a factor of ∼ 10 for isolated subhalos and by a factor of ∼ 6 for satellites. However, the reduction is mostly in the number of non-star-forming subhalos, and the studied model thus remains a viable candidate, taking into account the uncertainty in the Local Group total mass estimate. The formation of the first galaxies is also delayed, and the central densities of galaxies with v_max < 50 km/s are lowered: their circular velocities at 1 kpc from the centre are decreased and the radii of maximum circular velocity are increased. As for the stellar mass-metallicity and the stellar mass-halo mass relations, or the selection effects from tidal disruption, I find no significant differences between the models.