`Goldilocks would approve. Dark matter is not too cold and not too hot, but just right, researchers have found. Furthermore, its lukewarm temperature may help pinpoint just what the mysterious material is. [..]
According to their calculations, dark matter is “tepid” – about 10,000°C. By comparison, the surface of the Sun is about 6000°C, while its core is about 15.5 million °C.
“This temperature tells us something very fundamental about the properties of dark matter,” says Gilmore. He believes that tepid dark matter is almost certainly made up of a type of WIMP – massive theoretical particles that interact only weakly with other forms of matter, but attract or repel other WIMPs very strongly.’