Nonlinear kinetic Sunyaev-Zeldovich effect.

We derive fully nonlinear expressions for temperature fluctuations from the kinetic Sunyaev-Zeldovich (SZ) effect, the scattering of cosmic microwave background photons off hot electrons in bulk motion. Our result reproduces the Ostriker-Vishniac effect to second order in perturbation theory but contains nonlinear corrections to the electron velocities and densities that were neglected previously. We use the recently developed halo model for nonlinear gravitational clustering to compute the nonlinear kinetic SZ power spectrum, which dominates the primary anisotropy on small angular scales.

The onset of nonlinearity in cosmological structure.

We discuss the progression of growth of cosmological structure, from the quasilinear evolution of nearly Gaussian fluctuations on large scales into highly non-Gaussian, strongly nonlinear structure on small scales. A systematic development in perturbation theory describes the first departures from homogeneity but fails to reproduce the fully nonlinear results. Physical insight, conceptual models, and symmetries are useful in the strong clustering regime. A phenomenological model with input information from the quasilinear regime provides enticing results for the strongly nonlinear regime.

Constraints on galaxy bias, matter density, and primordial non-Gaussianity from the PSCz galaxy redshift survey.

We compute the bispectrum for the IRAS PSCz catalog and find that the galaxy distribution displays the characteristic signature of gravity. Assuming Gaussian initial conditions, we obtain galaxy biasing parameters 1/b(1) = 1.20(+0.18)(-0.19) and b(2)/b(2)(1) = -0.42+/-0.19, with no sign of scale-dependent bias for k < or = 0.3h Mpc(-1). These results impose stringent constraints on non-Gaussian initial conditions. For dimensional scaling models with chi(2)(N) statistics, we find N > 49, which implies a constraint on primordial skewness B3 < 0.35.