X-ray line spectroscopy for clusters of galaxies. I

Abstract

Theoretical models for the intracluster gas in X-ray clusters of galaxies are studied. The limits of validity of all the published models are derived from self-consistent arguments and existing data. Results are presented for the well model (gas trapped in the potential well of a single galaxy) and the wind model. A scaling law is proved that allows one to apply the results calculated for spherical systems to the nonspherical groupings that are often observed. The particular line intensities that can best be used to discriminate among theoretical models or to diagnose the gas (i.e., determine abundances, temperatures, ionization state, and other properties) are listed along with the required experimental sensitivity and resolution. Possible observing programs are described that can be carried out with existing instruments on currently operating satellites and with future space experiments (e.g., on HEAO-A, HEAO-B, and other planned X-ray missions).