Are you one of the authors of this paper? Email us from your institutional or work email address mentioning this article's arXiv ID and we'll verify you and give you edit access to this page.
Are you an author who sees something we missed or got wrong? Write to us — the subject line already carries the paper id. We read every note and correct the write-up.
Are you an author of this paper and would prefer our analysis not to be published? Email us from your institutional address; once confirmed, we will take the page down.
New observations prove that supernova remnants can accelerate protons to energies hundreds of times higher than those achievable by terrestrial accelerators.
When a massive star exhausts its thermonuclear fuel, its core collapses, and the outer layers are ejected into space at speeds of thousands of kilometers per second. This is how a supernova remnant is born — an expanding cloud of shock-compressed gas spanning light-years. One such object, IC 443, has long attracted the attention of astrophysicists: its structure hinted at processes capable of accelerating particles to energies unattainable in terrestrial laboratories. However, direct observational evidence was lacking.
The breakthrough came from the LHAASOobservatory, which detects gamma rays of the highest energies, so-called hard cosmic radiation. Its data revealed a compact source in IC 443 whose emission spectrum, the distribution of energy across frequencies, bears the imprint of protons accelerated to values hundreds of times exceeding the capabilities of the Large Hadron Collider. Such a spectrum arises when charged particles interact with magnetic fields and radiation in the vicinity of the source. Nearby, a pulsar is likely at work — a rapidly rotating neutron star left behind after the core collapse. Its powerful magnetic field, rotating with the star, generates directed radiation that may contribute to particle acceleration.
Earlier, the Fermitelescope detected gamma rays in the IC 443 region with a characteristic spectrum arising from head-on collisions of high-energy protons with nuclei of interstellar gas. This is a reliable indicator that a natural accelerator operates in the supernova remnant.
The discovery confirms the key role of supernova remnants as the main sources of cosmic rays — charged particles continuously bombarding Earth's atmosphere. The acceleration mechanism in IC 443, according to the data, is not fading: shock waves and magnetic fields continue to accelerate protons, as if a particle factory has been running nonstop for thousands of years.
