{"paper":{"title":"The peculiar GRB 110731A: Lorentz factor, jet composition, central engine, and progenitor","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ph"],"primary_cat":"astro-ph.HE","authors_text":"Alexei V. Filippenko, Bing Zhang, Enwei Liang, He Gao, HouJun L\\\"u, Lin Lan, Melissa L. Graham, Ruijing Lu, Weikang Zheng, Xianggao Wang","submitted_at":"2017-06-03T04:59:23Z","abstract_excerpt":"The jet compositions, central engines, and progenitors of gamma-ray bursts (GRBs) remain open questions in GRB physics. Applying broadband observations, including GRB prompt emission and afterglow properties derived from {\\em Fermi} and {\\em Swift} data, as well as from Keck host-galaxy observations, we address these questions for the peculiar, bright GRB 110731A. By using the pair-opacity method, we derive $\\Gamma_{0}>190$ during the prompt emission phase. Alternatively, we derive $\\Gamma_{0} \\approx 580$ and $\\Gamma_{0} \\approx 154$ by invoking the early-afterglow phase within the homogeneou"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1706.00898","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}