Non-Gaussianities from isocurvature modes

Understand

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.