http://arxiv.org/abs/1610.04862
In view of future high precision large scale structure surveys, it is important to quantify percent and sub-percent level effects in cosmological $N$-body simulations from which theoretical predictions are drawn. One such effect involves the choice of whether to set all modes above the one-dimensional Nyquist frequency, the so-called “corner” modes, to zero in the initial conditions. By comparing simulations with and without these modes, we find that at $z>6$, the difference in the matter power spectrum is large at wavenumbers just below $k_{\rm{Ny}}$, reducing to below 2% at all scales by $z\sim 3$. Including corner modes results in a better match between a low-resolution simulation and a high-resolution simulation at wavenumbers around the Nyquist frequency of the low-resolution simulation. The differences in mass functions are 3% for the smallest halos at $z=6$ for the simulation resolution studied here ($m_p \sim 10^{11}h^{-1}\,M_{\odot}$), but we find no significant difference in the stacked profiles of well-resolved halos at $z \leq 6$. Thus removing power at $k>k_{\rm{Ny}}$ in the initial conditions of cosmological simulations has a small effect on small scales and high redshifts, typically below a few percent, and may be important to take into account in simulations of the high redshift universe.
B. Falck, N. McCullagh, M. Neyrinck, et. al.
Tue, 18 Oct 16
16/70
Comments: 10 pages, 14 figures, submitted to ApJ