7 research outputs found
Models of inflation with primordial non-Gaussianities
We present a class of models in which the primordial metric fluctuations do
not necessarily obey Gaussian statistics. These models are realizations of
mechanisms in which non-Gaussianity is first generated by a light scalar field
and then transferred into curvature fluctuations during or at the end of
inflation. For this class of models we present generic results for the
probability distribution functions of the metric perturbation at the end of
inflation. It is stressed that finite volume effects can induce non trivial
effects that we sketch.Comment: 8 pages with 3 eps figures. To appear in Proceedings of the Albert
Einstein Century International Conference, UNESCO, Paris, France, 18-22 July
200
The shape of high order correlation functions in CMB anisotropy maps
We present a phenomenological investigation of non-Gaussian effects that
could be seen on CMB temperature maps. Explicit expressions for the temperature
correlation functions are given for different types of primordial mode
couplings. We argue that a simplified description of the radial transfer
function for the temperature anisotropies allows to get insights into the
general properties of the bi and tri-spectra. The accuracy of these results is
explored together with the use of the small scale approximation to get explicit
expressions of high order spectra. The bi-spectrum is found to have alternate
signs for the successive acoustic peaks. Sign patterns for the trispectra are
more complicated and depend specifically on the type of metric couplings. Local
primordial couplings are found to give patterns that are different from those
expected from weak lensing effects.Comment: 31 pages, 17 figures, submitted to Phys. Rev.
Constraints on mode couplings and modulation of the CMB with WMAP data
We investigate a possible asymmetry in the statistical properties of the
cosmic microwave background temperature field and to do so we construct an
estimator aiming at detecting a dipolar modulation. Such a modulation is found
to induce correlations between multipoles with . Applying this
estimator, to the V and W bands of the WMAP data, we found a significant
detection in the V band. We argue however that foregrounds and in particular
point sources are the origin of this signal.Comment: 14 pages, 14 figure
High order correlation functions for self interacting scalar field in de Sitter space
We present the expressions of the three- and four-point correlation functions
of a self interacting light scalar field in a de Sitter spacetime at tree order
respectively for a cubic and a quartic potential. Exact expressions are derived
and their limiting behaviour on super-horizon scales are presented. Their
essential features are shown to be similar to those obtained in a classical
approach.Comment: 8 pages, 4 figure
High order correlation functions for self interacting scalar field in de Sitter space
8 pages, 4 figuresWe present the expressions of the three- and four-point correlation functions of a self interacting light scalar field in a de Sitter spacetime at tree order respectively for a cubic and a quartic potential. Exact expressions are derived and their limiting behaviour on super-horizon scales are presented. Their essential features are shown to be similar to those obtained in a classical approach