Fossil groups of galaxies: seeing the future looking into the past

The nature of fossil groups of galaxies has been debated for over more than three decades. This is in part because of the lack of deep multiwavelength data and also due to the low purity of samples selected using solely magnitude gap criteria. The initial results of a sample of bona fide fossil groups using XMM, Chandra, HST & Gemini observations has clarified many of their characteristics, such as high central abundances and concentration. Recently developed dynamical ICL markers show very long ages, the longest than all clusters analyzed so far, perhaps having achieved the end of their merging trees. However, they exhibit hot cores, the nature of which is unknown. We show the comparison of different scenarios to explain the origin and maintenance of the hot cores, based on the analysis of intracluster gas metallicity ratios and suggest that superwinds-triggered by wet mergers with the BCG may be powerful enough to produce hot cores.