Non-Gaussianities from isocurvature modes
  This contribution discusses isocurvature modes, in particular the
non-Gaussianities of local type generated by these modes. Since the
isocurvature transfer functions differ from the adiabatic one, the coexistence
of a primordial isocurvature mode with the usual adiabatic mode leads to a rich
structure of the angular bispectrum, which can be decomposed into six
elementary bispectra. Future analysis of the CMB data will enable to measure
their relative weights, or at least constrain them. Non-Gaussianity thus
provides a new window on isocurvature modes. This is particularly relevant for
some scenarios, such as those presented here, which generate isocurvature modes
whose contribution in the power spectrum is suppressed, as required by present
data, but whose contribution in the non-Gaussianities could be dominant and
measurable.
