MG11 
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Abstract

The Matter Power Spectrum as a Tool to Discriminate Dark Matter--Dark Energy Interaction

The coincidence problem of late cosmic accelerationgets gets significantly alleviated when a suitable interaction between matter and dark energy, either of phantom type or not, enters the picture. We show that a class of models featuring this interaction fares rather well when contrasted with the anisotropies of the CMBR and the matter power spectrum. The latter test is very sensible to the interaction and may be used to discriminate between different models.

Bulk Viscosity Impact on the Scenario of Warm Inflation

The decay of the inflaton in radiation and particles during the slow roll suggests that these may interact with each other and that the latter may also decay into subproducts before inflation is completed. As a consequence, the fluid is no longer perfect and a non-negligible bulk viscosity necessarily sets in. We write the corresponding equations as an autonomous system and study the asymptotic behavior, the conditions for the existence of scaling solutions, and show that the late time effect of fluid dissipation alleviates the depletion of matter and increases the duration of inflation.

The Generalized Second Law in Dark Energy Dominated Universes

The generalized second law of gravitational thermodynamics is examined in scenarios where the dark energy dominates the expansion. For quintessence and phantom fields this law is fulfilled but it may fail when the dark energy is represented by a Chaplygin gas. However, if a black hole is allowed in the picture, the law can be violated if the field is of phantom type.