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Searching for isocurvature non-Gaussianity in the CMB trispectrum

Student thesis: Doctoral Thesis

Inflation was introduced to the Big Bang model of the universe as a method to solve the problems associated with this model. It also gave an explanation for the small scale inhomogeneities observed in the universe today. Since the concept was introduced, more complex models inflation have been postulated as time has gone on. However the amount of information available to measure the feasability of all these models has not grown at the same rate.

Very high precision measurements are now making it possible to start getting significant measurements of parameters measuring how non-Gaussian the distributions of perturbations from the inflation models are. These measurements have mostly been done using third order statistics, i.e. the bispectrum. The work presented in this looks at how good a measurement Planck will be able to make of non-Gaussian parameters using fourth-order statistics, i.e. the trispectrum.

In particular this work looks at models which have a second mode in addition to the standard adiabatic mode of the curvature perturbation, the isocurvature mode. These modes can be generated by models where there is more than one field present during inflation. Both these modes could be non-Gaussian, which gives rise to 17 parameters that can measure non-Gaussianity using the trispectrum. The aim of this work is to determine how good a measurement Planck could make of these parameters, especially considering they are not independent of each other. This work is presented in the context of determing bounds for model parameters for different inflation models.
Original languageEnglish
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Award dateFeb 2014

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