Small‐Scale Cosmic Microwave Background Temperature and Polarization Anisotropies Due to Patchy Reionization

We study contributions from inhomogeneous (patchy) reionization to arcminutescale ($1000 < \ell < 10,000$) cosmic microwave background (CMB) anisotropies.We show that inhomogeneities in the ionization fraction, rather than in themean density, dominate both the temperature and the polarization power spectra.Depending on the ionization history and the clustering bias of the ionizingsources, we find that rms temperature fluctuations range from 2 $\mu$K to 8$\mu$K and the corresponding values for polarization are over two orders ofmagnitude smaller. Reionization can significantly bias cosmological parameterestimates and degrade gravitational lensing potential reconstruction fromtemperature maps but not from polarization maps. We demonstrate that a simplemodeling of the reionization temperature power spectrum may be sufficient toremove the parameter bias. The high-$\ell$ temperature power spectrum willcontain some limited information about the sources of reionization.Comment: 11 pages, 8 figures. Minor changes to match version accepted by Ap