Pre-Big-Bang Cosmology and Circles in the Cosmic Microwave Background

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 ring 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 obtain a relation between the angular ring width and the angular radius of such circles that 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.

22 pages, 3 figures. A mistake in the width section is fixed, a few clarifications added in the text and typos corrected

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Cited by in corpus (6)

• On CCC-predicted concentric low-variance circles in the CMB sky
• Testing loop quantum cosmology
• Some conceptual issues in loop quantum cosmology
• CCC and the Fermi paradox
• Our Universe from the cosmological constant
• Seeing through the cosmological bounce: Footprints of the contracting phase and luminosity distance in bouncing models