  It is well known that processes of first order phase transitions may have
occurred in the inflationary era. If one or more occurred well before the end
of inflation, the nucleated bubbles are stretched to large scales and the
primordial power spectrum contains a scale dependent non-Gaussian component
provided by the remnants of the bubbles. We predict the anisotropies in the
cosmic microwave background (CMB) induced by inflationary bubbles. We build a
general analytic model for describing a bubbly perturbation; we evolve each
Fourier mode using the linear theory of perturbations from reheating until
decoupling; we get the CMB anisotropies by considering the bubbly perturbation
intersecting the last scattering surface. The CMB image of an inflationary
bubble is a series of concentric isothermal rings of different color (sign of
$\delta T/T$) on the scale of the sound horizon at decoupling ($\le 1^{o}$ in
the sky); the resulting anisotropy is therefore strongly non-Gaussian. The mean
amplitude of $\delta T/T$ for a bubble of size $L$ follows the known estimates
for linear perturbations, $\delta T/T\simeq\delta\rho /\rho\cdot
(L/H^{-1})^{2}$. In particular, 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 sub-degree angular scale, to be further
investigated and compared with the forthcoming high resolution CMB maps
provided by the MAP and the Planck experiments.
