Ultra-High Energy Cosmic Rays from Galactic Supernovae

Suppose that even the highest energy cosmic rays (CRs) observed on Earth are protons accelerated in local Milky Way Galaxy sources, with few if any from more distant sources. In this paper we treat the problem that supernovae remnants likely produce protons with energies up to about a PeV, but CRs with 100s of EeV energy are observed. We assume with minimal comment the idea that `new physics’ is at work and we accept that a CR’s collision energy at the Earth exceeds its kinetic energy as it travels through the Galaxy. There is some evidence that the collision energy-kinetic energy difference has been seen at the Tevatron and LHC, but it is small enough to attribute to standard physics. This sets the threshold for energy bifurcation. Based on this threshold and the CR spectrum endpoint, a formula for collision energy as a function of kinetic energy is derived. With the function and the observed CR spectrum we can predict the average spectrum of CR sources. Also we can estimate the collision energies of proton beams as terrestrial particle accelerators advance and produce beams with higher kinetic energies.

💡 Research Summary

The paper “Ultra‑High Energy Cosmic Rays from Galactic Supernovae” puts forward a bold, single‑origin hypothesis: every ultra‑high‑energy cosmic ray (UHECR) that reaches Earth, even those with energies of order 10^20 eV, is a proton accelerated in a supernova remnant (SNR) somewhere inside the Milky Way. The authors begin by recalling that standard diffusive‑shock‑acceleration (DSA) theory predicts a maximum proton energy of roughly 1 PeV (10^15 eV) for typical Galactic SNRs, far below the observed UHECR energies. To bridge this five‑order‑of‑magnitude gap they invoke a speculative new‑physics effect: the “collision energy” (the energy actually released when a cosmic‑ray proton strikes the Earth’s atmosphere) can exceed the proton’s kinetic energy during its interstellar voyage.

They point to very small, statistically insignificant discrepancies between the total energy measured in high‑energy proton–proton collisions at the Tevatron and the LHC and the energy expected from standard kinematics. Although these discrepancies are within experimental uncertainties, the authors treat them as a hint of an underlying threshold phenomenon. They posit that above a kinetic‑energy threshold of about 10^15 eV, the relationship between kinetic energy (E_K) and collision energy (E_C) changes from the trivial E_C ≈ E_K to a super‑linear form:

 E_C = E_K