Hyperfine Structure Radio Lines from Hot Gas in Elliptical Galaxies and Groups of Galaxies

Observations of intracluster gas bulk motions and turbulence in clusters and groups of galaxies should provide important information about physical conditions in the intergalactic gas. Thanks to the high spectral resolution of radio detectors, hyperfine structure (HFS) lines of highly-charged ions might help in this respect. Though not yet observed, intensities of emission and absorption HFS lines from the hot interstellar medium of elliptical galaxies and the intracluster medium of groups of galaxies are estimated to be on the limit of the abilities of existing instruments. The most interesting lines for this purpose are discussed.