Effect of Hot Baryons on the Weak-lensing Shear Power Spectrum

We investigate the impact of the intracluster medium on the weak-lensing shear power spectrum. The shear power spectrum depends on the total mass power spectrum. With the halo model, we find that the baryon power spectrum is significantly lower than the dark matter power spectrum on scales well below the linear scale. The effect on the shear power spectrum is much less pronounced. Nevertheless, the difference is on the order of a few percent for l & 1000, depending on the baryon profile and source redshift. In addition, cooling/cooled baryons and the intergalactic medium can further alter the shear power spectrum. Therefore, the small-scale baryon effect should be taken into account in order to interpret future weak lensing data for precision cosmology with high multipoles. Subject headings: cosmology: theory — dark matter — galaxies:clusters:general — gravitational lensing — large-scale structure of universe