Item

Abstract

The Hitomi results for the Perseus cluster have shown that accurate atomic
models are essential to the success of X-ray spectroscopic missions, and just
as important as knowledge on instrumental calibration and astrophysical
modeling. Preparing the models requires a multifaceted approach, including
theoretical calculations, laboratory measurements, and calibration using real
observations. In a previous paper, we presented a calculation of the electron
impact cross sections on the transitions forming the Fe-L complex. In the
present work, we systematically test the calculation against cross sections of
ions measured in an electron beam ion trap experiment. A two-dimensional
analysis in the electron beam energies and X-ray photon energies is utilized to
disentangle radiative channels following dielectronic recombination, direct
electron-impact excitation, and resonant excitation processes in the
experimental data. The data calibrated through laboratory measurements are
further fed into global modeling of the Chandra grating spectrum of Capella. We
investigate and compare the fit quality, as well as sensitivity of the derived
physical parameters to the underlying atomic data and the astrophysical plasma
modeling. We further list the potential areas of disagreement between the
observation and the present calculations, which in turn calls for renewed
efforts in theoretical calculations and targeted laboratory measurements.