Atomic Physics in X-ray Absorption Astrophysics

Tom Gorczyca

Western Michigan University

An outstanding challenge in modeling the chemical evolution of the universe is the determination of elemental abundances in terms of their various phases: atomic, molecular, and/or solid-state. The answer to this problem can be found through an analysis of X-ray telescope observations using a combination of independent disciplines, commonly grouped into the subfield of "Laboratory Astrophysics". These disciplines include astrophysical spectral modeling of the interstellar medium (ISM), experimental atomic physics measurements, and theoretical atomic physics calculations.

This talk will first give a brief review of x-ray spectroscopy and how it is used to study the chemical evolution of the universe. The underlying atomic physics processes will also be described, with an emphasis on the resonance process that are strongly imprinted on the observed x-ray spectra. Earlier calculations for photoabsorption in atomic carbon, oxygen, neon, magnesium, and silicon ions --- the abundant even nuclei --- will be discussed in relation to corresponding experimental measurements and observed spectra from x-ray satellites. I will conclude by discussing briefly the close similarity to recent work on photoabsorption in sulfur ions, measured here at Soleil and analyzed further during my visit to ISMO.

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