Cosmic microwave background temperature and polarization anisotropy in Brans-Dicke cosmology - art. no. 104036

We develop a formalism for calculating cosmic microwave background (CMB) te mperature and polarization anisotropies in cosmological models with Brans-D icke gravity. We then modify publicly available Boltzmann codes to calculat e numerically the temperature and polarization power spectra. Results are i llustrated with a few representative models. Comparing with the general-rel ativistic model of the same cosmological parameters, both the amplitude and the width of the acoustic peaks are different in the Brans Dicke models. W e use a covariance-matrix calculation to investigate whether the effects of Brans-Dicke gravity are degenerate with those of variation in other cosmol ogical parameters and to simultaneously determine whether forthcoming CMB m aps might be able to distinguish Brans-Dicke and general-relativistic cosmo logy. Although the predicted power spectra for plausible Brans-Dicke models differ from those in general relativity only slightly, we find that MAP an d/or the Planck Surveyor may in principle provide a test of Brans-Dicke the ory that is competitive to solar-system tests. For example, if all other pa rameters except for the CRIB normalization are fixed, a value of the Brans- Dicke parameter omega as large as 500 could be identified (at the 2 sigma l evel) with MAP, and for Planck, values as large as omega similar or equal t o 3000 could be identified; these sensitivities are decreased roughly by a factor of 3 if we marginalize over the baryon density, Hubble constant, spe ctral index, and re-ionization optical depth, In more general scalar-tensor theories, omega may evolve with time, and in this case, the CMB probe woul d be complementary to that from solar-system tests. [S0556-2821(99)01122-4] .