1303.2117 (Álvaro Villalobos et al.)

An improved prescription for merger time-scales from controlled simulations    [PDF]

Álvaro Villalobos, Gabriella De Lucia, Simone Weinmann, Stefano Borgani, Giuseppe Murante

We compare three analytical prescriptions for merger times available from the literature to simulations of isolated mergers. We probe three different redshifts, and several halo concentrations, mass ratios, orbital circularities and orbital energies of the satellite. We find that prescriptions available in the literature significantly under-predict long timescales for mergers at high redshift. We argue that these results have not been highlighted previously either because the evolution of halo concentration of satellite galaxies has been neglected (in previous isolated merger simulations), or because long merger times and mergers with high initial orbital circularities are under-represented (for prescriptions based on cosmological simulations). An explicit dependence on redshift in the original prescriptions as t_merger,modified(z) = (1+z)^0.44 t_merger, motivated by the evolution of halo concentration, gives a significant improvement in the predicted merger times up to ~20 t_dyn between 0View original: http://arxiv.org/abs/1303.2117