Chinese scientists have spotted the highest-energy photon yet: transforming our understanding of the Milky Way

The High-Altitudes Cosmological Ray Observatory (LHAASO), a major national scientific and technological infrastructure, has detected a large number of ultra-high-energy cosmic accelerators in the Milky Way galaxy, recording up to 1.4 bets of electron-volt gamma photons (bets = quadrillion), according to a statement from the Institute of High Energy Physics of the Chinese Academy of Sciences.

This is the highest energy photon ever observed, changing our traditional understanding of the Milky Way and ushering in the era of "ultra-high-energy gamma astronomy."

These findings were published in Nature on May 17, 2021. The research was carried out by the LHAASO International Collaboration, led by the Institute of High Energy Physics, Chinese Academy of Sciences.

The high-altitude cosmic ray observatory is still under construction, according to the report, which is based on 11 months of data from the half-size observatory that has already been completed in 2020.

Scientists found that the highest energy photons from star forming region in the constellation Cygnus is very active, also found 12 stable source of gamma rays, the photon energy has been extended to 1 near the electron volts, which is a number of the Milky Way located within the brightest LHAASO field gamma ray source, detect gamma photon signal is higher than the background more than 7 times the standard deviation, The source position measurement accuracy is better than 0.3°.

Although the data used this time is still limited, all sources that can be observed by LHAASO have gamma radiation above 0.1 betV, also known as "ultra-high energy gamma radiation." This suggests that the Milky Way is full of petaflov accelerators, and that the largest accelerator we have built on Earth (the LHC at CERN) accelerates particles to just 0.01 petaflov.

The LHAASO results completely break the "common sense" energy limit for cosmic ray accelerators in the Milky Way, which was previously predicted to be around the beat-electron volt range.

These findings opened the era of "ultra-high-energy gamma astronomy" observation, indicating that young massive star clusters, supernova remnants, pulsar clouds and other celestial bodies are the best candidates for accelerating ultra-high-energy cosmic rays in the Milky Way, helping to solve the "mystery of the century" of the origin of cosmic rays.

The results of LHAASO show that scientists need to re-understand the generation and propagation mechanism of energetic particles in the Milky Way galaxy, further study the extreme celestial phenomena and their related physical processes, and test the basic laws of physics under extreme conditions.

Cosmic rays are charged particles that travel through the universe at nearly the speed of light. They travel so fast that some of them carry enormous amounts of energy, for example, more than 100 times more than scientists on Earth have been able to accelerate particles in the Large Hadron Collider.

We have a name for the object that drives cosmic particles to accelerate into cosmic rays with great energy, the Beating Volt Cosmic Ray Accelerator, or Pevatron, according to the Institute of High Energy Physics of the Chinese Academy of Sciences. Where they are and what they are, we still don't have the answers, but this paper gives us some important clues.

But we've already confirmed the existence of the Pevatron in the Milky Way, and these findings bring us a step closer to understanding the origin of high-energy cosmic rays.