Galaxy clusters — in combination with CMB and BAO data — can provide precise constraints on the sum of neutrino masses .
However , these constraints depend on the calibration of the mass–observable relation .
For instance , the mass calibration employed in rules out the minimal 6-parameter \Lambda CDM model at 3.7 \sigma , and implies a sum of neutrino masses \sum m _ { \nu } = 0.39 \pm 0.10 .
By contrast , the mass calibration favored by from a self-consistent analysis of X-ray , SZ , and optical scaling relations is consistent with a minimal flat \Lambda CDM model with no massive neutrinos ( 1.7 \sigma ) , and is a better fit to additional data ( e.g . H _ { 0 } ) .
We discuss these results in light of the most recent SPT and ACT analyses , and the implications of our results on the current mild “ tension ” ( < 2 \sigma ) between CMB and BAO+ H _ { 0 } data .