Measuring the Dark Matter Equation of State and its Cosmological Consequences

MARIANO JAVIER DE LEON DOMINGUEZ ROMERO

Hotel del Lago, La Falda, Cordoba, Argentina

Conferencia; Grav 09; 2009

General Relativity and Gravitation Group@FaMAF - Universidad Nacional de Córdoba

The nature of the dominant component of galaxies and clusters remains unknown. While the astrophysics comunity supports the cold dark matter (CDM) paradigm as a clue factor in the current cosmological model, no direct CDM detections have been performed. Recently, Faber and Visser (2006) have suggested a simple method for measuring the dark matter equation of state. By combining kinematical and gravitational lensing data it is possible to test the widely adopted assumption of pressureles dark matter. According to this formalism, we have measured the dark matter equation of state using improved techniques and observations and find that is not as expected. In the light of this result, we can now suggest that our understanding of the gravitational processes involved in structure formation is  incomplete unless a complte general relativistic analysis is used. We have tested our techniques using simulations and we have also analyzed possible sources of errors that could invalidate or mimic our results.We explore the consequences of such measurement on the homogenous FRW universe dynamics and build an alternative cosmological scenario to the standart Lambda CDM universe. The new paradigm is based on the introduction of an effective scalar field reemplacing the undetected components of the dark  sector: dark matter and dark energy in the form of a cosmological constant.  We compute a minimal set of cosmological parameters wich allow us to reproduce several observational results like baryon abundance, constrains on the age of the universe, the astronomical scale of distance and the high redshift supernova data with a high degree of precision.