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Fossil Group Origins (FOGO) project : A multiwavelength view of Fossil galaxy groups

Jose Alfonso Lopez Aguerri (Institut d’astrophysique des Canaries)

Fossil groups are galaxy assosiations defined as X-ray bright systems
dominated in the optical by a giant elliptical galaxy at the center, and with an
R-band difference larger than 2 magnitudes between the two brightest galaxies located within half of the virial radius of the system. Numerical simulations show that these galaxy associations assembled most of their mass at high redshift and remanin undisturbed for a long period of time. In this picture, fossil groups would be the last step of the galaxy cluster evolution. The lack of a large and homogeneus statistical study of this kind of systems makes that previous results were not conclusive, and the previous view of these systems was very simplistic.
The Fossil Groups Origins (FOGO) project (Aguerri et al. 2010) has started a
systematic and multiwavelength study of a large sample of 34 FGs. I will present in this seminar some of the observational properties obtained so far in the framework of the FOGO project. In particular, I will show the photometrical properties of the brightest groups galaxies, and the dymanics and the galaxy luminosity functions of some FGs of the sample.