Dark Matter may be hot stuff

"Cold, dark matter" has a certain ring to it, but new simulations of our corner of the cosmos suggest that dark matter – the stuff that is thought to underlie the universe – might be warm, with relatively fast-moving and lightweight particles.

In cosmology's standard model, dark matter is cold, made up of relatively heavy low-energy particles, and will happily settle into structures as small as planets.

Hot dark matter has already been ruled out because its particles would move too fast for galaxies to form. But warm dark matter has smaller, faster particles that still allow for our familiar starry sky.

Most computer models produce a generic universe that doesn't resemble ours in detail, but Gustavo Yepes at the Autonomous University of Madrid, Spain, and his collaborators on the Constrained Local Universe Simulations (CLUES) project have tuned theirs to resemble the galaxies and clusters nearest Earth.