Geometrical constraints on dark energy
Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern, 0315 Oslo, Norway e-mail: email@example.com
2 Department of Physics, University of Oslo, PO Box 1048, Blindern, 0316 Oslo, Norway
3 Oslo College, Faculty of Engineering, Cort Adelers gt. 30, 0254 Oslo, Norway
Accepted: 23 September 2004
We explore the recently introduced statefinder parameters. After reviewing their basic properties, we calculate the statefinder parameters for a variety of cosmological models, and investigate their usefulness as a means of theoretical classification of dark energy models. We then go on to consider their use in obtaining constraints on dark energy from present and future supernovae type Ia data sets. We find that it is non-trivial to extract the statefinders from the data in a model-independent way, and one of our results indicates that parametrizing the dark energy density as a polynomial of second order in the redshift is inadequate. Hence, while a useful theoretical and visual tool, applying the statefinders to observations is not straightforward.
Key words: cosmology: theory / cosmology: cosmological parameters
© ESO, 2005