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Searching for Oscillations in the Primordial Power Spectrum

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Daan Meerburg, Princeton University
04 October 2013 from 11:00 AM to 12:15 PM
320 Whitmore Lab
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The Planck data provided unprecedented detail of the small fluctuations in the cosmic microwave background (CMB). We know now that these fluctuations are adiabatic, Gaussian and almost scale invariant. This constrains models and model parameters of the early Universe, but despite the quality of the data they remain inconclusive of the details. In particular, small deviations from scale invariance are still permitted, and so are small levels of non-Gaussianity. In recent years models have been proposed which predict oscillatory features on top of an almost scale invariant spectrum. The amplitude and frequency of these oscillations is usually associated with fundamental parameters of the model, be that the axion decay constant in axion-monodromy inflation, or the energy scale at which particles are injected into the free vacuum during inflation in more exotic models. In this talk I will present a new method to search for these, potentially really small, features in the CMB data. I will show the method recovers oscillations in Planck-like simulated data at a few times 10^{-2} level. I will argue that our method is fast, reliable and allows for much more accurate search of features than other existing methods.  After this, I will present our findings after applying this same technique to the WMAP9 and Planck data. I will address the significance of several intriguing hints in the data, using simulations.