On the starting redshift for cosmological simulations: Focusing on halo properties

Understand

We systematically study the effects of varying the starting redshift z_i for cosmological simulations in the highly non-linear regime.

• Our primary focus lies with the (individual) properties of dark matter halos -- namely the mass, spin, triaxiality, and concentration -- where we find that even substantial variations in z_i leave only a small imprint, at least for the probed mass range M \in [10^{10}, 10^{13}] Msun/h and when investigated at redshift z=0.
• We further compare simulations started by using the standard Zel'dovich approximation to runs based upon initial conditions produced with second order Lagrangian perturbation theory.
• Here we observe the same phenomenon, i.e.