SUBDEGREE COSMIC MICROWAVE BACKGROUND ANISOTROPIES FROM INFLATIONARY BUBBLES

It is well known that processes of first-order phase transitions may h ave occurred in the inflationary era. If one or more occurred well bef ore the end of inflation, the nucleated bubbles would have been stretc hed to large scales and the primordial power spectrum would contain a scale-dependent non-Gaussian component provided by the remnants of the bubbles. We predict the anisotropies in the cosmic microwave backgrou nd (CMB) induced by inflationary bubbles. We build a general analytic model for describing a bubbly perturbation, evolve each Fourier mode u sing the linear theory of perturbations from reheating until decouplin g, and get the CMB anisotropies by considering the bubbly perturbation intersecting the last scattering surface. The CMB image of an inflati onary bubble is a series of concentric isothermal rings of different c olor (sign of delta T/T) on the scale of the sound horizon at decoupli ng (less than or equal to 1 degrees in the sky); the resulting anisotr opy is therefore strongly non-Gaussian. The mean amplitude of delta T/ T for a bubble of size L follows the known estimates for linear pertur bations, delta T/T similar or equal to delta rho/rho(L/H-1)(2). In par ticular, bubbles with size corresponding to the seeds of the observed large-scale voids (tens of comoving Mpc) induce an interesting pattern of CMB anisotropies on the subdegree angular scale, to be further inv estigated and compared with the forthcoming high-resolution CMB maps p rovided by the Microwave Anisotropy Probe (MAP) and the Planck experim ents.