I am currently investigating the physics that drives the gas accretion onto galaxies using the “Evolution and Assembly of GaLaxies and their Environments” (EAGLE) suite of hydrodynamical cosmological simulations. I find that the gas accretion rate onto galaxies increases with halo mass until the hot halo forms and then flattens. The flattening is the result of the hot halo, that acts as a preventive feedback mechanism. At the moment I am developing a physically motivated model of gas accretion rate onto galaxies that accurately reproduces the gas accretion rates from the EAGLE simulations... Stay tuned!
I am using the EAGLE suite of hydrodynamical cosmological simulations to investigate the hot hydrostatic halo formation and its impact on galaxy evolution. I find that a bimodality in the distribution of cooling time of gas in the halo is a clear signature of hot halo formation. I use it to determine the mass scale at which the hot halo forms. I calculate the amount of hot gas in the halo and find that the presence of energy sources, like supernova (SN), impacts on the hot halo by increasing the amount of hot gas at large radii and reducing the mass scale of hot halo formation. Active galactic nuclei, on the contrary, do not seem to affect the hot halo as strongly as SN... Stay tuned!
I developed a semi-analytic, physically motivated model for dark matter halo concentration as a function of halo mass and redshift. The semi-analytic model combines an analytic model for the halo mass accretion history (Correa et al. 2015a), based on extended Press Schechter (EPS) theory, with an empirical relation between concentration and formation time obtained through fits to the results of numerical simulations (Correa et al. 2015b). Because the semi-analytic model is based on EPS theory, it can be applied to wide ranges in mass, redshift and cosmology. The resulting concentration-mass (c-M) relations are found to agree with the simulations, and because the model applies only to relaxed halos, they do not exhibit the upturn at high masses or high redshifts found by some recent works... Get the paper here!
I developed an analytic model of halo mass accretion histories using the extended Press-Schechter formalism. In Correa et al. (2015a) I show that the halo mass history is well described by an exponential function of redshift in the high-redshift regime. However, in the low-redshift regime the mass history follows a power law because the growth of density perturbations is halted in the dark energy dominated era due to the accelerated expansion of the Universe. I then provide an analytic model that depends on cosmology and on the linear matter power spectrum. In Correa et al. (2015b) I explore the relation between the structure and mass accretion histories of dark matter halos using a suite of cosmological simulations. I then provide a semi-analytic model for halo mass history that combines analytic relations with fits to simulations. The model depends on halo concentration and formation time. Find out more in Correa et al. (2015a) here and Correa et al. (2015b) here.