From the initial conditions of the Universe to our own Milky Way

Annalisa Pillepich

January 16, 2013

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Abstract: Within the LambdaCDM ansatz, numerical simulations have successfully reproduced the large-scale structure of the Universe that we observe today under the form of groups and clusters of galaxies, filaments, and sheets. On smaller scales, on the other hand, our understanding of the physical processes that lead to the variety of observed galaxy properties is still inadequate, and such are the simulations which include baryonic physics. In this talk I will both challenge some of the assumptions that characterize the dark sector of the concordance model and thus the large scales, as well as I will present one of the most realistic up to date cosmological N-body/smooth particle hydrodynamic (SPH) simulation of the formation of a close analog of a Milky Way disk galaxy, the Eris simulation and its dark-matter-only twin ErisDark. I will show how primordial non-Gaussianity can help us to discriminate among competing scenarios for the generation of cosmological perturbations and thus to unveil the nature of one of the key ingredients that sets up the initial conditions of the standard model: Inflation. I will show how primordial non-Gaussianity affects the statistical properties of the (dark) matter distribution at high and low redshift and thus how it can be measured via the abundance and spatial clustering of galaxy groups and galaxy clusters from current and future surveys. Within the Gaussian assumption, I will give an account of the outstanding issues in galaxy formation theory and will present our most recent progresses in understanding the effects that gas dynamics, supernova feedback, and star-formation recipes have on the global properties and dark- matter profiles of a Milky-Way-like halo and on its satellite population.