Is the cosmic-ray flux cutoff above 4 * 10^19 eV a GZK effect? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: Is the cosmic-ray flux cutoff above $4e19\,\mathrm{eV}$ a GZK effect?
Revision 2: Is the cosmic-ray flux cutoff above $4 \times 10^{19}\,\mathrm{eV}$ a GZK effect?
Plain · changed
Revision 1: Very few cosmic rays arrive above about 4e19 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.
Revision 2: 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 · changed · core
Revision 1: Determine whether the suppression of the ultra-high-energy cosmic-ray flux at $E > \sim 4e19\,\mathrm{eV}$ 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 $1e18\,\mathrm{V}$ with composition getting heavier at higher energy. Answer: yes or no for a dominant GZK origin, with the proton fraction above $5e19\,\mathrm{eV}$ and the implied cosmogenic neutrino flux.
Revision 2: 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.
Settled by
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 $1\mathrm{e}17 \text{ to } 1\mathrm{e}19\,\mathrm{eV}$.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
contested
Status note
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.
Posed since
1966

Decisions