Impact of dark matter substructure on the matter and weak-lensing power spectra

We explore the effect of substructure in dark matter halos on the power spectrum and bispectrum of matter fluctuations and weak-lensing shear. By experimenting with substructure in a cosmological N = 512(3) simulation, we find that when a larger fraction of the host halo mass is in subhalos, the resulting power spectrum has less power at 1 less than or similar to k less than or similar to 100 h Mpc(-1) and more power at k greater than or similar to 100 h Mpc(-1). We explain this effect using an analytic halo model including subhalos, which shows that the 1 less than or similar to k less than or similar to 100 h Mpc(-1) regime depends sensitively on the radial distribution of subhalo centers, while the interior structure of subhalos is important at k greater than or similar to 100 h Mpc(-1). The corresponding effect on the weak-lensing power spectrum due to substructures is up to similar to 11% at angular scale l less than or similar to 10(4). Predicting the nonlinear power spectrum to a few percent accuracy for future surveys would therefore require large cosmological simulations that also have exquisite numerical resolution to model accurately the survivals of dark matter subhalos in the tidal fields of their hosts.