Speaker
Description
In this talk I present the evolution of the star formation rates (SFRs) / stellar masses of galaxies and the dark matter halo mass accretion histories (MAHs) for the last 13 billion years of the Universe. The observed star formation rate-stellar mass (SFR-M*) relation and the "observed" cosmic star formation rate density (CSFRD) represent both important canvases for our current knowledge of galaxy formation and are both routinely used to constrain cosmological models. I employ cosmological simulations combined with radiative transfer and demonstrate that the adopted methodology / indicator (e.g. IR, UV, Ha, SED) to obtain the observed galaxy SFRs and stellar masses are bound to heavily affect the derived properties something that I further show by comparing results from different observational studies. In addition, I demonstrate that state-of-the-art simulations (EAGLE, TNG, Simba, semi-analytic models) are found to suffer from troubling limitations mostly connected to resolution effects and the adopted feedback prescriptions which have to be reconsidered. Last, I demonstrate that the observed star formation rate density and Cosmic Mass accretion History can be described by only two parameters and a function that resembles a Gamma growth, like numerous other physical processes in Nature (from Economy to Biology) while it has a plateau from z = 1-4 and not a strong peak at z = 2. I proceed to show that Dark matter halo growth follows the same Gamma growth pattern using an analysis of Mass accretion Histories that covers halos from 1 solar mass to 1000 trillion solar masses.
