Dark matter is slowly running out of places to hide. Two new looks at the gamma-ray sky suggest that if the mysterious matter is a particle, it is heavier than 40 gigaelectronvolts, about 44 times the mass of a proton.
That contradicts hints from three experiments on Earth that pointed to a lightweight dark matter particle weighing just a quarter as much, although some researchers say such featherweights are still in the running.
Dark matter makes up about 80 per cent of the matter in the universe, but no one is sure what it's made of.
The leading candidate is a WIMP, or weakly-interacting massive particle, that was produced in the big bang and has been clumping up and seeding structures such as galaxies ever since. Physicists know how much dark matter the universe contains in total, but not how much each individual WIMP weighs.
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