Astronomers might have found where the most high-energy rays in the universe come from, mysterious particles that shoot out of an equally mysterious source: the very biggest black holes.
Black holes in the centres of galaxies are known mostly for sucking everything in – even light, which is why no one can see them. However, in the process, they also spew something out: cosmic rays, which likely are bits of torn-apart atoms that shoot across the universe at close to the speed of light.
These are 100 million times more energetic than anything actively produced by the most powerful particle smashers on Earth, and are even more energetic than the rays from an exploding star. Bursts of these rays periodically slam into Earth’s upper atmosphere, and this collision scatters bits of debris smaller than atoms down to Earth’s surface.
Now, astronomers from nearly 90 universities and observatories around the globe have traced the primary sources of these rays. They say ” supermassive” black holes at the centres of galaxies, each holding the mass of several billion stars, are firing out particles and electromagnetic radiation from gamma and X-rays to ultraviolet, visible and infrared light, and radio waves.
The discovery comes from the Auger Collaboration, the international drive to find the origin of these cosmic rays. (Pierre Auger was a French physicist who, in 1938, discovered showers of debris particles from cosmic rays).
The streaking ray also produces a trail of light in the air, caused by excited nitrogen atoms. It can be visible if it happens at night.