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Constraints on non-Gaussianity in string-inspired inflation

Sarah E. Shandera (Columbia University, ISCAP)
05 July 2007, 14:15 - 16:00

Primordial non-gaussianity (NG) is potentially very data rich, providing a means to rule out otherwise attractive inflation scenarios. Single-field models with sound speed less than one (including the string theory motivated DBI model) can have strongly scale dependent NG, with the tensor/scalar ratio falling as the magnitude of NG increases. Such a model could easily evade the CMB constraints but still have important effects at scales responsible for the formation of cosmological objects such as clusters and galaxies. We compute the effect of such NG on cluster number counts as a function of redshift, making use of techniques to go beyond the usual $f_{NL}$ formalism to capture scale-dependent features. We report constraints on these models imposed by current data and forecast constraints achievable with forthcoming measurements.
Shandera.pdf [6129 KBytes]