A point-like cosmic particle accelerator pumps out PeV gamma rays stronger than expected from a pulsar 50x weaker than Crab.

What makes this discovery remarkable is not just the energy, but the efficiency. This system appears to convert energy into high-speed particles far more effectively than current physics says it should.

In simple terms, astronomers may have found a cosmic particle accelerator that outperforms even their best theoretical designs.

To understand the breakthrough, it helps to know what scientists were looking at. A pulsar wind nebula forms when a dead star, called a pulsar, spins rapidly and blasts out a stream of charged particles at nearly the speed of light.

A detector buried deep in Antarctic ice has captured the first experimental evidence of a predicted but never-before-seen phenomenon: radio pulses generated when high-energy cosmic rays slam into the ice sheet and trigger particle cascades inside it. Through results published in Physical Review Letters, astronomers of the Askaryan Radio Array (ARA) Collaboration have validated a key technique, which they hope will eventually allow them to detect some of the rarest and most energetic particles in the universe.

In 1962, Soviet physicist Gurgen Askaryan predicted that high-energy particles passing through a dense material should produce a distinctive burst of radio waves. When such a particle strikes an atom, it triggers a cascade of secondary particles that sweeps up electrons from the surrounding material, creating a negatively charged shower front that radiates at radio frequencies.

This “Askaryan radiation” was later confirmed in lab experiments and detected in air, but observing it in ice proved far more challenging. This is partly due to the difficulty of distinguishing genuine signals from the many sources of radio noise in polar environments, and partly because the simulations needed to model the effect in ice have only recently become sophisticated enough to make such rigorous analysis possible.

The Large High Altitude Air Shower Observatory (LHAASO) has detected PeV (10¹⁵ eV) gamma-ray emission from a pulsar wind nebula powered by PSR J1849-0001 in the constellation Aquila, marking the discovery of a new PeVatron and posing a challenge to the classical theory of particle acceleration in pulsar wind nebulae.

This discovery is important because the calculated particle acceleration efficiency of this celestial structure approaches or even exceeds the theoretical limits allowed under ideal magnetohydrodynamic conditions.

This study, published in Nature Astronomy, was conducted by Prof. Liu Ruoyu, Dr. Wang Kai, and doctoral student Tong Chaonan from Nanjing University, Prof. Chen Songzhan and Assoc. Prof. Wang Lingyu from the Institute of High Energy Physics of the Chinese Academy of Sciences, and their collaborators.