MG14 - Talk detail

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If we live on the weak brane with zero effective cosmological constant in a warped 5D bulk spacetime, gravitational waves and brane fluctuations can be generated by a part of the 5D Weyl tensor and carries information of the gravitational field outside the brane. We consider on a cylindrical symmetric warped FLRW background a U(1) self-gravitating scalar-gauge field without bulk matter. It turns out that "branons" can be formed dynamically, due to the modified energy-momentum tensor components of the cosmic string. As a result, we find that the late-time behavior could be significant deviate from the standard evolution of the universe. The effect is triggered by the time-dependent warpfactor and the modified brane equations, comparable with a dark energy effect. This is a brane-world mechanism, not present is standard 4D FLRW, where the large disturbances are rapidly damped as the expansion proceed. Because gravity can propagate in the bulk, the cosmic string can build up a huge angle deficit (or mass per unit length) by the warpfactor. Disturbances in the spatial components of the stress-energy tensor cause cylindrical symmetric waves, amplified due to the presence of the bulk space and warpfactor. They could survive the natural damping due to the expansion of the universe. This long range effect could also explain the recently found spooky alignment of quasars in vast structures in the cosmic web.

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Abstract

After the perception that superstring theory predicts the existence of cosmic superstrings, a new revival of the self-gravitating U(1) scalar-gauge field solution emerged. On a 5D warped brane world space time, there will be observable imprint of these cosmic superstrings on the induced effective 4D brane metric for values of the symmetry breaking scale much larger than the GUT scale. In a time-dependent setting, it seems that there is wave-like energy-momentum transfer to infinity on the brane, a high-energy brane world behaviour. For a zero effective cosmological constant (Randall-Sundrum fine-tuning) brane fluctuations (‘branons’) can be induced by the interaction of the scalar-gauge field and the bulk Weyl tensor. The disturbances don’t fade away during the expansion due to the warp factor. An analytic solution is found for this warp factor from the bulk Einstein equations. Because these cosmic strings can build up a huge mass per unit length in the bulk, they can induce massive KK-modes felt on the brane.

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