The Metal Content of the Hot Atmospheres of Galaxy Groups
By Fabio Gastaldello
Galaxy groups host the majority of matter and more than half of all the galaxies in the Universe. Their hot (107 K), X-ray emitting intra-group medium (IGrM) reveals emission lines typical of many elements synthesized by stars and supernovae. Because their gravitational potentials are shallower than those of rich galaxy clusters, groups are ideal targets for studying, through X-ray observations, feedback effects, which leave important marks on their gas and metal contents. In this paper we reviewed the history and present status of the chemical abundances in the IGrM probed by X-ray spectroscopy.
We discussed the limitations of our knowledge, in particular due to uncertainties in the modeling of the key spectral feature of the Fe-L shell by plasma codes. We highlight the bright future prospect in this field as there will be a revolution in the study of the X-ray spectra provided by the microcalorimeter X-IFU on board Athena with its unprecedented resolving power allowing to derive metal abundances with exquisite accuracy. The WFI will be a complementary highly valuable instrument to trace the metal content of group out to redshift 1.