We study the structure and evolution of dark matter halos from z = 300 to z = 6 for two cosmological N -body simulation initialization techniques .
While the second order Lagrangian perturbation theory ( 2lpt ) and the Zel ’ dovich approximation ( za ) both produce accurate present day halo mass functions , earlier collapse of dense regions in 2lpt can result in larger mass halos at high redshift .
We explore the differences in dark matter halo mass and concentration due to initialization method through three 2lpt and three za initialized cosmological simulations .
We find that 2lpt induces more rapid halo growth , resulting in more massive halos compared to za .
This effect is most pronounced for high mass halos and at high redshift , with a fit to the mean normalized difference between 2lpt and za halos as a function of redshift of \mu _ { \Delta M _ { \mathrm { vir } } } = ( 7.88 \pm 0.17 ) \times 10 ^ { -3 } z - ( 3.07 \pm 0.14 ) % \times 10 ^ { -2 } .
Halo concentration is , on average , largely similar between 2lpt and za , but retains differences when viewed as a function of halo mass .
For both mass and concentration , the difference between typical individual halos can be very large , highlighting the shortcomings of za -initialized simulations for high- z halo population studies .