A survey of X-ray light from galaxy clusters has found no evidence of dark matter decaying, in the latest in a series of contradictory results.

In 2014, two separate teams found an unexpected bump in the energy spectra of dozens of galaxy clusters. Emissions at 3.55 kiloelectronvolts (keV) were seen as a possible sign of the decay of 'sterile' neutrinos with a mass of 7.1 keV. Physicists have hypothesized that these heavier cousins of the three known types of neutrino are possible components of dark matter.

Now astronomer Florian Hofmann at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and his team have analysed publicly available data from the Chandra X-ray Observatory concerning 33 galaxy clusters (11 of which were not included in the original studies). Their search found no evidence of an anomalous bump at around 3.55 keV.

Astron. Astrophys. 592, A112 (2016)