Is the cosmic-ray flux cutoff above $4 \times 10^{19}\,\mathrm{eV}$ a GZK effect?
In plain words
Very few cosmic rays arrive above about $4 \times 10^{19}$ eV, either because they lose energy on the leftover light of the Big Bang (the GZK effect) or because their sources cannot push them higher.
Precise statement
Determine whether the suppression of the ultra-high-energy cosmic-ray flux at $E > \sim 4 \times 10^{19}\,\mathrm{eV}$ is mainly due to propagation losses (photopion production on the cosmic microwave background for protons, photodisintegration for nuclei) or to source maximum rigidity of a few $10^{18}\,\mathrm{V}$ with composition getting heavier at higher energy. Answer: yes or no for a dominant GZK origin, with the proton fraction above $5 \times 10^{19}\,\mathrm{eV}$ and the implied cosmogenic neutrino flux.
What would settle it
A composition measurement above $5\mathrm{e}19\,\mathrm{eV}$ with per-event mass resolution, and detection or exclusion of the cosmogenic neutrino flux at $1\mathrm{e}17 \text{ to } 1\mathrm{e}19\,\mathrm{eV}$.
Status in the literature
Auger shower-depth data favor a mixed composition that becomes heavier with energy and a source cutoff, while Telescope Array reports spectral differences from Auger at the highest energies.
Parent problems
- Special case of Which sources accelerate cosmic rays above $10^{19}\,\mathrm{eV}$? · open · from revision 1 The parent was revised since revision 1: it now states another question.
Results
No results have been posted on this problem yet.
Post a result · how results are checked
Sign in to follow or save this problem
Comments (0)
Comments are not records: they are not signed, stamped or logged. How comments work
No comments yet.
Sign in to comment.