Telescopes find missing matter in cosmic cobwebs

Mysterious bursts come from remote galaxy

1 Astronomers have observed fast radio bursts, typically from remote galaxies. They are thought to be triggered by neutron stars with powerful magnetic fields, known as magnetars. The bursts last only a few milliseconds, but they emit more energy than the Sun does over several decades.

Ultrathin hydrogen clouds delay long waves

2 If the universe was entirely empty, then short and long radio waves would travel at the same speed. But the radio waves pass by thin, millions-of-degrees-hot hydrogen clouds, and are refracted a little, like light through a prism. This delays long radio waves more than short ones.

Radio telescope records wave delay

3 The ASKAP telescope array in Australia observes fast radio bursts from remote galaxies and the time lag between short and long wavelengths in the bursts. The more delay experienced by long waves compared with short ones, the more hydrogen gas a burst has passed on