[1104.3688] Pre-Big-Bang Cosmology and Circles in the Cosmic Microwave Background
|Authors:||William Nelson, Edward Wilson-Ewing|
|Abstract:||We examine the possibility that circles in the cosmic microwave background could be formed by the interaction of a gravitational wave pulse emitted in some pre-big-bang phase of the universe with the last scattering surface. We derive the expected size distribution of such circles, as well as their typical width and (for concentric circles) angular separation. We apply these results in particular to conformal cyclic cosmology, ekpyrotic cosmology as well as loop quantum cosmology with and without inflation in order to determine how the predicted geometric properties of these circles would vary from one model to the other, and thus, if detected, could allow us to differentiate between various pre-big-bang cosmological models. We also show that the angular width and the sine of the angular radius of such circles are inversely proportional. This relation can be used in order to determine whether or not circles observed in the cosmic microwave background are due to energetic pre-big-bang events.|
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Pre-big-bang cosmological scenarios are attractive because they avoid the initial curvature singularity. This interesting paper studies how different pre-big-bang models can be tested using circles of anomalously low temperature variance that may exist in the Cosmic Microwave Background.