New detector finds gamma rays from surprising cosmic sources

HAIZI MOUNTAIN, China (AP) — Astrophysicist Cao Zhen opens a steel hatch on a windswept Tibetan Plateau and climbs down a ladder into inky darkness. His flashlight picks out a boat floating on a pool of purified water above thousands of glittering orbs the size of beachballs.

He’s inside a $175 million observatory that has already discovered something tantalizing astronomers even before the observatory is technically complete: bursts of gamma rays from outer space that may someday help explain how matter is created and distributed across the universe.

The Large High Altitude Air Shower Observatory, the biggest device of its kind, has detected a dozen sources of ultra high-energy gamma rays, according to a study in the journal Nature, from what Cao calls “many hot spots,” in our Milky Way galaxy.

Gamma rays with such high energy have never been detected before, and the findings suggest these rays can come not just from dying stars, but are also generated inside massive young stars.

“These results are really stunning — some of the most exciting I have ever seen,” said Alan Watson, an astrophysicist working with the Pierre Auger Observatory in Argentina.

Cao’s team traced 530 high-energy gamma rays to 12 sources including a massive cluster of young stars called the Cygnus Cocoon and the interstellar cloud called the Crab Nebula.

Gamma rays are a type of extreme radiation generated by the hottest and brightest explosions in the universe, like when a large star implodes. Those implosions also create the matter that make up planets — and everything that lives on them, including us. Of all the electromagnetic waves in the universe, gamma rays have the smallest wavelengths and the most energy. They can release more energy in 10 seconds than our sun in 10 billion years.

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