We present templates for the Sunyaev-Zel'dovich (SZ) angular power spectrum
based on four models for the nonlinear gas distribution. The
frequency-dependent SZ temperature fluctuations, with thermal (TSZ) and kinetic
(KSZ) contributions, are calculated by tracing through a dark matter
simulation, processed to include gas in dark matter halos and in the
filamentary intergalactic medium. Different halo gas models are compared to
study how star formation, energetic feedback, and nonthermal pressure support
influence the angular power spectrum. The standard model has been calibrated to
reproduce the stellar and gas fractions and X-ray scaling relations measured
from low redshift clusters and groups. The other models illustrate the current
theoretical and empirical uncertainties relating to properties of the
intracluster medium. Relative to the standard model, their angular power
spectra differ by approximately 50% (TSZ), 20% (KSZ), and 40% (SZ at 148 GHz)
for l=3000, sigma_8=0.8, and homogeneous reionization at z=10. The angular
power spectrum decreases in amplitude as gas mass and binding energy is removed
through star formation, and as gas is pushed out to larger radii by energetic
feedback. With nonthermal pressure support, less pressure is required to
maintain hydrostatic equilibrium, thus reducing the thermal contribution to the
SZ power. We also calculate the SZ templates as a function of sigma_8 and
quantify this dependence. Assuming C_l is proprotional to (sigma_8/0.8)^alpha,
the effective scaling index ranges from 7<alpha_tsz<9, 4.5<alpha_ksz<5.5, and
6.5<alpha_sz(148 GHz)<8 at l=3000 for 0.6<sigma_8<1. The template spectra are
publicly available and can be used when fitting for the SZ contribution to the
cosmic microwave background on arcminute scales.Comment: 14 pages, 10 figures, to be submitted to Ap
