Å®ÉúСÊÓƵ

Read more: Click here to read a longer version of this story

DARK matter may hold clues to a mysterious excess of light in the universe – thanks to the outcast stars it seems to harbour.

Galaxies are thought to be wrapped in haloes of dark matter that extend far beyond the galaxies’ visible mass. When they collide, some stars get ripped out by gravitational forces, creating trailers of light called tidal tails (see impression).

While most of these stars sink back into the merged galaxy, a few may become trapped in dark matter haloes. Such stars haven’t been found yet. But a new sky map made with NASA’s Spitzer Space Telescope shows that the model is a good fit for otherwise unexplained splotches of light in the cosmic infrared background, a haze of light thought to be the collective glow of all the stars and galaxies that have ever existed (Nature, ).

More work is needed to confirm the idea, says NASA’s Edward Wright. The new research looked at a larger area of sky than ever before, but Spitzer’s sensitivity is limited. When the James Webb Space Telescope is completed in 2018, its advanced infrared eye should give more details.