Effects of inflationary bubbles on the polarization and temperature anisotropies of the cosmic microwave background

We predict the imprint of linear bubbly perturbations on the polarization a nd temperature anisotropies of the cosmic microwave background (CMB). We model analytically a bubbly density perturbation at the beginning of the radiation-dominated era and we apply the linear theory of cosmological per turbations to compute its time evolution. At decoupling, it uniquely marks the CMB polarization and temperature anisotropy sky. As predicted by recent general work regarding spatially limited cosmological seeds, during evolut ion the perturbation propagates beyond the size of the bubble and it reache s the CMB sound horizon in the time considered. Therefore, its signal appea rs as a series of concentric rings, each characterized by its own amplitude and sign, on the scale of the sound horizon at decoupling (less than or eq ual to 1 degrees on the sky). Polarization and temperature rings are strict ly correlated; photons coming from the centre of the bubble are not polariz ed, because of the spherical symmetry of the present problem. As expected f or linear perturbations with size L and density contrast delta at decouplin g, delta T/T is roughly delta(L/H-1)(2); the polarization is about 10 per c ent of the temperature anisotropy. We predict the impact of a distribution of bubbles on the CMB polarization and temperature power spectra. Considering models containing both cold dark matter (CDM) Gaussian and bubbly non-Gaussian fluctuations, we simulate an d analyse 10 degrees x 10 degrees sky patches with angular resolution of ab out 3.5 arcmin. The CMB power associated with the bubbles is entirely on su bdegree angular scales (200 less than or equal to l less than or equal to 1 000), which will be explored by the forthcoming high-resolution CMB experim ents with per cent precision. Depending on the parameters of the bubbly dis tribution, we find extra power with respect to the ordinary CDM Gaussian fl uctuations; we infer simple analytical scalings of the power induced by bub bly perturbations and we constrain our parameters with the existing data.