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We extend our previous study of the cool gas responsible for the emission ofOVII X-ray lines in the cores of clusters and groups of galaxies. This is thecoolest X-ray emitting phase and connects the 10,000 K H {\alpha} emitting gasto the million degree phase, providing a useful tool to understand cooling inthese objects. We study the location of the O VII gas and its connection to theintermediate Fe XVII and hotter O VIII phases. We use high-resolution X-raygrating spectra of elliptical galaxies with strong Fe XVII line emission anddetect O VII in 11 of 24 objects. Comparing the O VII detection level andresonant scattering, which is sensitive to turbulence and temperature, suggeststhat OVII is preferably found in cooler objects, where the FeXVII resonant lineis suppressed due to resonant scattering, indicating subsonic turbulence.Although a larger sample of sources and further observations is needed todistinguish between effects from temperature and turbulence, our results areconsistent with cooling being suppressed at high turbulence as predicted bymodels of AGN feedback, gas sloshing and galactic mergers. In some objects theOVII resonant-to-forbidden line ratio is decreased by either resonantscattering or charge-exchange boosting the forbidden line, as we show for NGC4636. Charge-exchange indicates interaction between neutral and ionized gasphases. The Perseus cluster also shows a high Fe XVII forbidden-to- resonanceline ratio, which can be explained with resonant scattering by low-turbulencecool gas in the line-of-sight.

Insights into the location and dynamics of the coolest X-ray emitting gas in clusters of galaxies