THE X-RAY-SPECTRA OF CLUSTER COOLING FLOWS .1. OPTICALLY THIN MODELS

Optically thin X-ray spectra have been calculated for a set of cluster cooling flow models including homogeneous models and flows with strong gas loss. We find that models with gas loss have lower total X-ray luminosities than homogeneous models by a factor of at most 1.35. The integrated surface brightness profiles for models with gas loss are much less centrally peaked than the profiles for models with no gas loss. Emergent X-ray spectra from 0.1 to 10 keV are presented for the cooling flow as a whole as well as for three apertures centered on the flow. The total X-ray spectra for the various models are quite similar. For spatially resolved spectra, however, the homogeneous models show enhanced soft X-ray line emission in the central regions of the flow as compared to the gas-loss models. In the outer regions of the cooling flow, the gas-loss models exhibit much more soft X-ray line emission. Surface brightness profiles, aperture luminosities, and line profiles for a set of X-ray lines have also been calculated. For homogeneous models, the profiles for lines produced at low temperatures are very centrally concentrated, since the majority of the cooling occurs within the sonic radius. In models with gas loss, the cooling is distributed throughout the flow region producing a more extended surface brightness profile. The line shapes for several strong lines have also been calculated. For lines produced at lower temperatures, the homogeneous models produce broad, flat integrated line profiles. The central line shapes in these models are double peaked. For inhomogeneous models and lines produced at higher temperatures, the line shapes are nearly Gaussian. X-ray observations of line profiles such as these could provide direct evidence that the gas in cluster cooling flows is actually flowing. The feasibility of observations such as these with future X-ray missions is discussed.