Light from space has record-breaking energy

Twelve gamma ray hot spots suggest our galaxy harbors powerful particle accelerators

LHAASO observatory

The LHAASO observatory (shown) is in China. It observes very high-energy light. This observatory’s detectors, spread across a wide area, will eventually cover more than a square kilometer (more than one-third square mile).

Institute of High Energy Physics/Chinese Academy of Sciences

The cosmos keeps outdoing itself.

Extremely energetic light from space is an unexplained wonder. Scientists don’t know where that light comes from, exactly. And now astronomers have spotted this light, called gamma rays, at higher energies than ever before.

You can’t see gamma rays with your eyes. They are much more energetic than the light that we can see. So you need a fancy detector to spot them. The Large High Altitude Air Shower Observatory, LHAASO, is an experiment in China. It searches for extremely high energy gamma rays.

LHASSO spotted more than 530 of these brilliant rays with more than 0.1 quadrillion electron volts of energy. The highest-energy of these gamma rays was about 1.4 quadrillion electron volts. That’s a lot. And its the highest-energy light ever seen.

Previously, the most energetic gamma ray known had less than a quadrillion electron volts.

For comparison, the super-energetic protons in the largest particle accelerator on Earth — the Large Hadron Collider — only reach trillions of electron volts.

The researchers reported their new observations online May 17 in Nature.

Scientists spotted 12 gamma-ray hot spots. These are parts of the sky from which the gamma rays emanate.

Those hot spots hint that our galaxy, the Milky Way, has powerful particle accelerators. But those particle accelerators aren’t made by humans. Instead, they come from violent events in the cosmos. They might be exploding stars, for example. Such violent events make electric and magnetic fields. Those can speed up protons and electrons. Those fast particles can then produce gamma rays with a lot of energy. That can happen when protons interact with other matter in space, for example.

Scientists aren’t sure what could produce gamma rays with the extreme energies observed. But the new observations point to two possibilities. One hot spot was associated with the Crab Nebula. That’s the turbulent remains of an exploded star. Another possible source was the Cygnus Cocoon. That’s a region where massive stars are forming. The stars blast out intense winds in the process.

LHAASO is located on Haizi Mountain in China’s Sichuan province. It is not yet fully operational. It’s due to be completed later this year. Then, it could find even more gamma rays.

Science News physics writer Emily Conover studied physics at the University of Chicago. She loves physics for its ability to reveal the secret rules about how stuff works, from tiny atoms to the vast cosmos.

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