Talk detail

Participant	Pavon, Diego
Institution	Autonomous University of Barcelona - Campus Bellaterra - Bellaterra - Catalonia - Spain

Session	CM2	Accepted	Yes	Order	6	Time	15:35 - 15:45
Talk	Oral abstract	Title	Why we need dark energy
Co-authors	Ninfa Radicella
Abstract	It is argued that dark energy -or something dynamically equivalent at the background level- is necessary if the expanding universe is to behave as and ordinary macroscopic system; that is, if it is to tend to some thermodynamic equilbrium state in the long run.

Session	CM3	Accepted	Yes	Order	3	Time	15:00 - 15:20
Talk	Oral abstract	Title	Thermodynamic constraints on the emergent universe
Co-authors	Sergio del Campo and Ramon Herrera
Abstract	We argue that the emergent universe proposed by Ellis and Maartens, CQG 21(2004) 223, is consistent with the generalized second law of thermodynamics provided the radiation component does not contribute largely to the total entropy density of the static phase. In general, most emergent scenarios are expected to fulfill this loose constraint.

Session	CM2	Accepted	Yes	Order	7	Time	15:45 - 16:00
Talk	Oral abstract	Title	Parmetrizing the deceleration parameter
Co-authors
Abstract	We propose and constrain with the latest observational data three parameterizations of the deceleration parameter, valid from the matter era to the far future. They are well behaved and do not diverge at any redshift. On the other hand, they are model independent in the sense that the only assume that the Universe is homogeneous and isotropic at large scales.