Resonant scattering in galaxy clusters for anisotropic gas motions on   various spatial scales
  The determination of characteristic amplitudes and anisotropy of hot gas motions in galaxy clusters from observations of the brightest resonance lines is discussed. Gas motions affect (i) the spectral line shape through the Doppler effect and (ii) the radial surface brightness profiles in lines during resonant scattering. Radiative transfer calculations have been performed by the Monte Carlo method in the FeXXV resonance line at 6.7 eV for the Perseus cluster (Abell426). It was shown that (a) radial motions reduce the scattering efficiency much more dramatically than purely tangential motions; (b) large-scale gas motions weakly affect the scattering efficiency. The uncertainty in measuring the characteristics of gas motions using resonant scattering has been estimated for existing and future observations of clusters. 
I. Zhuravleva, E. Churazov, S. Sazonov, R. Sunyaev, K. Dolag
astro-ph.HE