Spectroscopy with the New Generation of X-Ray Observatories

The reliable extraction of physical information from astrophysical x-ray spectra depends upon the accuracy and completeness of plasma emission codes, which have become standard tools for the analysis of spectroscopic data from cosmic x-ray sources. These codes are designed to process atomic data and synthesize model spectra for the cosmically abundant elements over a wide range of temperatures and densities and often need to accommodate the presence of an ionizing radiation field. The upcoming launches of AXAF , XMM and Astro-E will usher in a new era of astrophysical x-ray spectroscopy, characterized by large collecting area, broad bandpass and order-of-magnitude improvements in spectral resolving power. The highly detailed spectra to be acquired with the new satellite observatories will present major challenges for analysts, plasma spectroscopists and atomic physicists. In fact, results from the ASCA and EUVE missions have already exposed problems in plasma codes, attributable to inadequacies in the incorporated atomic data. Revisions of the atomic database are being pursued along three avenues: atomic modeling, laboratory experiments and astrophysical observations. I will draw upon recent results in x-ray astronomy to establish the framework in which to discuss some of the problems faced by atomic modelers in the push to improve plasma emission codes.