2023MNRAS.521.1794F

We have recently uncovered Hidden Cooling Flows (HCFs) in the XMM Reflection Grating Spectrometer spectra of three clusters of galaxies; Centaurus, Perseus, and A1835. Here, we search for them in a wider sample of objects: the X-ray brightest group NGC 5044; four moderate X-ray luminosity clusters Sersic 159, A262, A2052, and RX J0821; and three high X-ray luminosity clusters RX J1532, MACS 1931, and the Phoenix cluster. Finally, we examine two Virgo elliptical galaxies, M49 and M84. All statistically allow the addition of an HCF. We find a significant detection of an HCF in six clusters and two elliptical galaxies. The hidden mass cooling rates are $5{\!-\!}40\hbox{$\hbox{$\rm \, {\rm M}_{\odot }$}{\rm \, yr}^{-1}\, $}$ for the normal clusters, $1000\hbox{$\hbox{$\rm \, {\rm M}_{\odot }$}{\rm \, yr}^{-1}\, $}$ or more for the extreme clusters, and $1{\!-\!}2\hbox{$\hbox{$\rm \, {\rm M}_{\odot }$}{\rm \, yr}^{-1}\, $}$ for the elliptical galaxies. We discuss the implications of the results for the composition of the innermost parts of the massive host galaxies and look forward to future observations.