Baryons and weak lensing power spectra

We provide a simple toy model to elucidate the effects of baryonic cooling on predictions of the convergence power spectrum in weak gravitational lensing. Our model suggests that the effects of baryonic cooling on dark matter halo profiles can alter the dark matter power spectrum at k similar to 10h Mpc(-1) and lead to percent level changes in the convergence angular power spectrum at wavenumbers of several thousand. These effects would be measurable with planned weak lensing surveys and will impact constraints on cosmological parameters. (C) 2004 Elsevier B.V. All rights reserved.