{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"eeb2b1a0be4baf36cfb2b01afc9096eef4f014706c93d1a1f5eeab79a0e22db7","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["a84b556fc0a19e1560d217d39c7de30082b6ac641b93f76796f13aed4954812e","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"cb866f78827bad4999472ebb031bc1186887b3364d12209a8431e678a1d91710","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"astro.grb-engines-jets.jet-composition","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"The jet may carry its energy mainly as magnetic field or as hot gas and light; the two pictures predict different signals.","posed_since":"","precise":"Determine the magnetization $\\sigma = B'^{2}/(4\\pi\\rho' c^{2})$, with B' the comoving magnetic field and rho' the comoving rest-mass density, of GRB jets at the dissipation radius $r \\sim 10^{13} \\text{ to } 10^{16}\\,\\mathrm{cm}$, distinguishing Poynting-dominated ($\\sigma >> 1$) from fireball ($\\sigma << 1$) jets, using the strength of a thermal photospheric component, prompt gamma-ray polarization degree and early reverse-shock optical emission. Answer: $\\sigma$ at the emission radius for the bulk of bursts, with evidence.","problem_ref":"a84b556fc0a19e1560d217d39c7de30082b6ac641b93f76796f13aed4954812e","references":"","settled_by":"Time-resolved prompt gamma-ray polarimetry on a sample of bright bursts combined with early optical reverse-shock measurements.","status_note":"","title":"Are GRB jets dominated by magnetic energy or hot matter?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"91b0eb0ed9de5af4f60591b6f3da9960669095256f0d3effeafac6a97664ae10","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"cfe055e770b1d329a598dce9b7988319a2f2b2672fe8818d0fa23793888cfc84","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"_krmO5GSIIuy51Ty5izWkifPBL7jBvIUYoC_uFphLO0UgUu7GnUAoXio3OBj9CZrU_3mAjdj4Asb7CH_ITLbDA"},"schema":"pubphys.envelope/1"},"record_hash":"91b0eb0ed9de5af4f60591b6f3da9960669095256f0d3effeafac6a97664ae10","leaf_index":2368}