Coming of age in the dark sector: how dark matter haloes grow their gravitational potential wells

Abstract

We present a detailed study of how dark matter haloes assemble their mass and\ngrow their (central) potential well. We characterize these via their mass\naccretion histories (MAHs) and potential well growth histories (PWGHs), which\nwe extract from the Bolshoi simulation and from semi-analytical merger trees\nsupplemented with a method to compute the maximum circular velocity, Vmax, of\nprogenitor haloes. The results of both methods are in excellent agreement, both\nin terms of the average and the scatter. We show that the MAH and PWGH are\ntightly correlated, and that growth of the central potential precedes the\nassembly of mass; the maximum circular velocity is already half the present day\nvalue by the time the halo has accreted only 2 percent of its final mass.\nFinally, we demonstrate that MAHs have a universal form, which we use to\ndevelop a new and improved universal model that can be used to compute the\naverage or median MAH and PWGH for a halo of any mass in any LCDM cosmology,\nwithout having to run a numerical simulation or a set of halo merger trees.\n