The Effects of Varying Cosmological Parameters on Halo Substructure
  We investigate how different cosmological parameters, such as those delivered
by the WMAP and Planck missions, affect the nature and evolution of dark matter
halo substructure. We use a series of flat $\Lambda$ cold dark matter
($\Lambda$CDM) cosmological $N$-body simulations of structure formation, each
with a different power spectrum but the same initial white noise field. Our
fiducial simulation is based on parameters from the WMAP 7th year cosmology. We
then systematically vary the spectral index, $n_s$, matter density, $\Omega_M$,
and normalization of the power spectrum, $\sigma_8$, for 7 unique simulations.
Across these, we study variations in the subhalo mass function, mass fraction,
maximum circular velocity function, spatial distribution, concentration,
formation times, accretion times, and peak mass. We eliminate dependence of
subhalo properties on host halo mass and average over many hosts to reduce
variance. While the "same" subhalos from identical initial overdensity peaks in
higher $\sigma_8, n_s$, and $\Omega_m$ simulations accrete earlier and end up
less massive and closer to the halo center at $z=0$, the process of continuous
subhalo accretion and destruction leads to a steady state distribution of these
properties across all subhalos in a given host. This steady state mechanism
eliminates cosmological dependence on all properties listed above except
subhalo concentration and $V_{max}$, which remain greater for higher $\sigma_8,
n_s$ and $\Omega_m$ simulations, and subhalo formation time, which remains
earlier. We also find that the numerical technique for computing scale radius
and the halo finder used can significantly affect the concentration-mass
relationship computed for a simulation.
