COT3 - Nonsingular Cosmology |
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Speaker |
Bastero-Gil, Mar |
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Co-autors |
D. Santos, J. Macias-Perez |
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Talk Title |
Non-linear preheating with metric perturbations and gravitational waves |
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Abstract |
We present preliminary results for the evolution of the coupled system field-gravity during preheating after inflation, integrating the full set of Einstein equations with matter sources provide by the inflaton field and fields coupled to it. Parametric amplification of gravitational waves during preheating have been previously studied including only the dominant source term due to the field fluctuations, and these results show that in certain class of models a background of primordial gravity waves is generated within the possible reach of future gravity wave experiments. But tensor modes are also sourced by scalar (and vector) metric perturbations. In order to estimate their possible effect we have first studied the evolution of the system including only scalar metric perturbations. The induced preheating of the scalar metric perturbations is not large enough to backreact onto the fields, but for exaple in hybrid inflation it is enough to generate a non-negligible source term in the evolution equation for tensor and vector fluctuations. We therefore have studied the evolution of the full set of equations in a generic hybrid model. This also takes into account the effect of the expansion rate during preheating. The preliminary results obtained by varying the Hubble expansion rate show a tendency to reduce the value of the amplitude of the primordial gravitational waves compared to previous results without taking into accound the expansion rate. |
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