Atomic excitations in relativistic heavy-ion collisions

In the past two decades, relativistic collisions of highly-charged ions (HCI) with different target materials helped extent our understanding of the light-matter coupling into the regime of strong Coulomb fields. In particular, measurements of the angular distribution and polarization of x-rays, emitted in such collisions, have revealed much information about this coupling of the radiation field, and how it is affected by the inner-atomic interactions of the ions. -- In this talk, I shall review some of the recent progress in describing the dynamics of few-electron HCI and explain how theoretical predictions help in the analysis and interpretation of experiments. Details about the excitation and decay of HCI can be obtained especially from a stepwise description of the individual processes in terms of the density matrix. Well-known excitation processes of HCI refer to the radiative and dielectronic recombination as well as to Coulomb and electron-impact collisions. Moreover, I shall discuss how theoretical data, when compared to accurate measurements, (may) facilitate to extract nuclear magnetic moments of rare radioactive isotopes or small level splittings of HCI that are otherwise inaccessible.