X-Ray Spectroscopy and Atomic Data

The Laboratory Astrophysics program employing the Lawrence Livermore National Laboratory (LLNL) Electron Beam Ion Trap (EBIT) has been providing useful atomic data in support of the x-ray missions Chandra and XMM-Newton. Major achievements have been made for Fe-L ions in hot, collisional plasmas, relevant to stellar coronae, supernova remnants, elliptical galaxies, and galaxy clusters. Measurements for L-shell ions of other cosmically important elements are also required, some of which are in the LLNL EBIT pipeline. On the other hand, data for inner-shell excited lines relevant to photoionized plasmas near accretion sources are largely lacking. Even the wavelengths of these lines are only poorly known, which severely limits their use for diagnostics, despite the great potential.