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G. V. Brown (LLNL), P. Beiersdorfer (LLNL), K. R. Boyce (GSFC), H. Chen (LLNL), K. C. Gendreau (GSFC), J. Gygax (GSFC), S. M. Kahn (Columbia), R. L. Kelley (GSFC), F. S. Porter (GSFC), C. K. Stahle (GSFC), A. E. Szymkowiak (GSFC), D. Thorn (LLNL), E. Träbert (LLNL)
Consistent, accurate fits to the spectra provided by ASCA of the x-ray emission originating in the centers of clusters of galaxies containing cooling flows have not been possible. The discrepancies have been attributed to overly-simple cooling flow models and inaccurate and incomplete atomic data used by the spectral analysis packages. The atomic data used in the models, i.e., those contained in XSPEC, have come almost invariably from calculations. However, using the LLNL electron beam ion trap (EBIT), a spare Astro-E/XRS microcalorimeter system, and flat-crystal spectrometers for higher-resolution measurements, we are producing an essentially complete atomic data set for Fe K- and L-shell radiation consisting of transition wavelengths and relative intensities as a function of Maxwellian temperature. This experimental atomic data set in addition to the cooling flow models provided by standard fitting packages will be used to fit spectra of clusters of galaxies. Replacing ca! lculated atomic data by measurments reduces or eliminates the uncertainties associated with the atomic data, and we are able to assess the validity of the cooling flow models with higher confidence. As a first test of this approach, we fit the ASCA spectrum of the Centaurus cluster.
Work by the UC-LLNL was performed under the auspices of DOE under contract W-7405-ENG-48 and supported by NASA Space Astrophysics Research and Analysis grants to LLNL, GSFC, and Columbia University.