{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"532c086be417f00f9a08e481dabe9deefc57ef627484436ea13f44438b55209d","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"841fe66a058c9e7c684c89ee531dff1829c62a906d69c1123117a201fc506617","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":"1","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 $r \\sim 1e13 \\text{ to } 1e16\\,\\mathrm{cm}$, 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":null,"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":"d34ff2cb4f455ed6abcd7339be502ac934cb4f47f2fd2df51ba89febba9c8dd6"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a84b556fc0a19e1560d217d39c7de30082b6ac641b93f76796f13aed4954812e","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"78ad05eb7ac49656755861eeeef856b25961de5f7deb22852a6e98b74a3efd72","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"td7RPVMYk9Zs94Yimm-XLxA2-Rd7pi3Fa3pnb9Mhz5iyXUmT4fjvs2i4eDRqaqn2iyMRPs6KbfnCeSfgJcQoBA"},"schema":"pubphys.envelope/1"},"record_hash":"a84b556fc0a19e1560d217d39c7de30082b6ac641b93f76796f13aed4954812e","leaf_index":547}