Matter at extremes of density and temperature occurs widely in astrophysical objects such as giant gas planets or highly evolved stars. Accurate modelling of matter at high energy density (HED) is of great importance in understanding the structure and evolution of these objects . Creation of electromagnetic HED plasmas in the laboratory requires very powerful drivers. Intense heavy ion pulses from the GSI and FAIR facility allow generation of matter in the regime of warm dense matter . Bright x-ray sources produced by high-energy and intense laser pulses are ideally suited to penetrate and diagnose such dense plasmas. The unique combination of the GSI accelerator with the short-pulse high-energy laser PHELIX  enables advanced pump-probe schemes for characterizing the HED samples.