Assaf Ben-David, Ben Rathaus, Nissan Itzhaki
We consider a universe with a non-classical stringy topology that has fixed points. We concentrate on the simplest example, an orbifold point, and study its observable imprints on the cosmic microwave background (CMB). We show that an orbifold preserves the Gaussian nature of the temperature fluctuations, yet modifies the angular correlation function. A direct signature of an orbifold is a single circle in the CMB that is invariant under rotation by 180 degrees. Searching the 7-year ILC map of WMAP, we find one candidate circle and show that its high statistical significance is due to foreground contamination. We place a lower bound on the distance to an orbifold point at ~85% of the distance to the surface of last scattering. We show that due to galactic foregrounds, a more realistic bound is direction dependent and considerably lower.
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http://arxiv.org/abs/1207.6218
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