{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"895b1134c0c1bf0bc91339dc126edf2426507718f41d3609e0b43b5b3c2a3956","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["8ecb14e2c3c6c3893178d62a714b2311ab089e4d28e1924508b2c9e861fe5e89","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"5c60d02abb5730d47972352dc956a09f083f59e3bc28b7bf3eeeefbe47c5da2c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"astro.cosmic-ray-origins.suppression-cause","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"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.","posed_since":"1966","precise":"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.","problem_ref":"8ecb14e2c3c6c3893178d62a714b2311ab089e4d28e1924508b2c9e861fe5e89","references":"","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 $1\\mathrm{e}17 \\text{ to } 1\\mathrm{e}19\\,\\mathrm{eV}$.","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.","title":"Is the cosmic-ray flux cutoff above $4 \\times 10^{19}\\,\\mathrm{eV}$ a GZK effect?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"63ea71d7ef136ffc787a4983d3127eecebea90084975880e33b36d2e2ceaec6f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"cac890784fb076b7bc671eefb56d3f46714d5597f323d2d3aacc3886daf8d123","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"4J4nrVGQlk_ODE9IvJUO8IN70CQmWDvB8uvi2bc5fCjSU9QjZqeS8EirZsg-anq0dJNMg3Pd7sZrbtiPGi30Aw"},"schema":"pubphys.envelope/1"},"record_hash":"63ea71d7ef136ffc787a4983d3127eecebea90084975880e33b36d2e2ceaec6f","leaf_index":2338}