{"paper":{"title":"Numerical Simulations of an Initially Top-Hat Jet and the Afterglow of GW170817$\\,$/$\\,$GRB170817A","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"Fabio De Colle, Gerardo Urrutia, Jonathan Granot, Ramandeep Gill","submitted_at":"2019-02-27T02:01:51Z","abstract_excerpt":"The afterglow of GRB$\\,$170817A/GW$\\,$170817 was very unusual, slowly rising as $F_\\nu\\propto{}t_{\\rm{}obs}^{0.8}\\nu^{-0.6}$, peaking at $t_{\\rm{obs,pk}}\\sim\\,150\\;$days, and sharply decaying as $\\sim{}t_{\\rm{}obs}^{-2.2}$. VLBI observations revealed an unresolved radio afterglow image whose flux centroid moved superluminally with $v_{\\rm{app}}\\approx4c$, clearly indicating that the afterglow was dominated by a relativistic jet's compact core. Different jet angular structures explained the afterglow lightcurves: Gaussian and steep power-law profiles with narrow core angles $\\theta_c\\lesssim5^\\"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1902.10303","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/1902.10303/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}