Salafia, Om SharanOm SharanSalafiaGHISELLINI, GabrieleGabrieleGHISELLINIGHIRLANDA, GiancarloGiancarloGHIRLANDAColpi, M.M.Colpi2024-02-222024-02-2220180004-6361http://hdl.handle.net/20.500.12386/34814We show that the delay between GRB170817A and GW170817 is incompatible with de-beamed emission from an off-axis relativistic jet. The prompt emission and the subsequent radio and X-ray observations can instead be interpreted within a giant-flare-like scenario, being the result of a relativistic outflow driven by the ultra-strong magnetic field produced by magnetohydrodynamic amplification during the merger of the progenitor double neutron-star binary. Within such a picture, the data indicate that the outflow must be endowed with a steep velocity profile, with a relatively fast tail extending to Γ ∼ 8. Since the conditions for the launch of such an outflow are relatively general, and the presence of a velocity profile is a natural expectation of the acceleration process, most neutron star binary mergers should feature this quasi-isotropic, hard X-ray emission component, that could be a powerful guide to the discovery of additional kilonovae associated to relatively nearby gravitational wave events.STAMPAenArticle10.1051/0004-6361/2017322592-s2.0-85056219439https://arxiv.org/abs/1711.03112https://www.aanda.org/articles/aa/full_html/2018/11/aa32259-17/aa32259-17.html2018A&A...619A..18SFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation