The Mass Profile and Accretion History of Cold Dark Matter Halos

Understand

We use the Millennium Simulation series to study the relation between the accretion history (MAH) and mass profile of cold dark matter halos.

• We find that the mean density within the scale radius, r_{-2} (where the halo density profile has isothermal slope), is directly proportional to the critical density of the Universe at the time when the main progenitor's virial mass equals the mass enclosed within r_{-2}.
• Scaled to these characteristic values of mass and density, the mean MAH, expressed in terms of the critical density of the Universe, M(\rho_{crit}(z)), resembles that of the enclosed density profile, M(<\rho >), at z=0.
• Both follow closely the NFW profile, suggesting that the similarity of halo mass profiles originates from the mass-independence of halo MAHs.