The Milky Way's Most Powerful Particle Accelerator

Astronomers have pinpointed an object in our Galaxy that acts as a natural particle accelerator, surpassing the capabilities of any machine built on Earth. Located near the star Altair, this source, known as LHAASO J1912+1014u, emits protons at energies exceeding a peta electron volt. These particles are a thousand times more energetic than those produced by the Large Hadron Collider.

Identifying this object required solving a specific puzzle. While observatories first detected high-energy gamma rays from this region in 2024, gamma rays can originate from two sources. They are either the byproduct of protons colliding with gas or the result of fast-moving electrons. The initial data lacked the resolution to distinguish between these two possibilities, leaving the nature of the source in question.

A research team led by Tsunefumi Mizuno from Hiroshima University provided the solution by combining data from three different sources. They integrated gamma ray readings from NASA’s Fermi telescope, radio observations of interstellar gas from the FUGIN survey, and X-ray data from the Chandra Observatory. No single instrument provided a definitive answer, but the combined dataset confirmed the presence of a proton accelerator.

The findings show that the gamma ray emissions align perfectly with the surrounding interstellar gas, which suggests that protons are slamming into the gas clouds. Furthermore, the X-ray data lacked the signatures expected from electron-based emission. This confirms the location as a PeVatron, an astrophysical source capable of accelerating particles to peta electron volt energies.

This discovery provides more than just a single confirmation. It establishes a reliable method for astronomers to classify the dozens of other PeVatron candidates currently identified across the Milky Way. By bundling data from multiple instruments, researchers can now filter out mundane stellar debris and focus on the most powerful particle accelerators in space.