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Centro de Astrofísica da Universidade do Porto

The ΛCDM limit of the generalized Chaplygin gas scenario

P. P. Avelino, L. M. G. Beça, J. P. M. de Carvalho, C. J. A. P. Martins

We explicitly demonstrate that, contrary to recent claims, the dynamics of a generalized Chaplygin gas model with an equation of state p = -C (where C is a positive constant) is equivalent to that of a standard LambdaCDM model to first order in the metric perturbations. We further argue that the analogy between the two models goes well beyond linear theory and conclude that they cannot be distinguished based on gravity alone.

dark matter, dark energy theory, cosmological perturbation theory

Journal of Cosmology and Astroparticle Physics
Volume 9, Page 002_1
September 2003

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Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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