Troja, E.E.TrojaPIRO, LUIGILUIGIPIROvan Eerten, H.H.van EertenWollaeger, R. T.R. T.WollaegerIm, M.M.ImFox, O. D.O. D.FoxButler, N. R.N. R.ButlerCenko, S. B.S. B.CenkoSakamoto, T.T.SakamotoFryer, C. L.C. L.FryerRicci, R.R.RicciLien, A.A.LienRyan, R. E.R. E.RyanKorobkin, O.O.KorobkinLee, S. -K.S. -K.LeeBurgess, J. M.J. M.BurgessLee, W. H.W. H.LeeWatson, A. M.A. M.WatsonChoi, C.C.ChoiCOVINO, StefanoStefanoCOVINOD'AVANZO, PaoloPaoloD'AVANZOFontes, C. J.C. J.FontesGonzález, J. BecerraJ. BecerraGonzálezKhandrika, H. G.H. G.KhandrikaKim, J.J.KimKim, S. -L.S. -L.KimLee, C. -U.C. -U.LeeLee, H. M.H. M.LeeKutyrev, A.A.KutyrevLim, G.G.LimSánchez-Ramírez, R.R.Sánchez-RamírezVeilleux, S.S.VeilleuxWieringa, M. H.M. H.WieringaYoon, Y.Y.Yoon2020-09-032020-09-0320170028-0836http://hdl.handle.net/20.500.12386/27082A long-standing paradigm in astrophysics is that collisions—or mergers—of two neutron stars form highly relativistic and collimated outflows (jets) that power γ-ray bursts of short (less than two seconds) duration. The observational support for this model, however, is only indirect. A hitherto outstanding prediction is that gravitational-wave events from such mergers should be associated with γ-ray bursts, and that a majority of these bursts should be seen off-axis, that is, they should point away from Earth. Here we report the discovery observations of the X-ray counterpart associated with the gravitational-wave event GW170817. Although the electromagnetic counterpart at optical and infrared frequencies is dominated by the radioactive glow (known as a ‘kilonova’) from freshly synthesized rapid neutron capture (r-process) material in the merger ejecta, observations at X-ray and, later, radio frequencies are consistent with a short γ-ray burst viewed off-axis. Our detection of X-ray emission at a location coincident with the kilonova transient provides the missing observational link between short γ-ray bursts and gravitational waves from neutron-star mergers, and gives independent confirmation of the collimated nature of the γ-ray-burst emission.STAMPAenArticle10.1038/nature242902-s2.0-85032832066000414222900046https://www.nature.com/articles/nature242902017Natur.551...71TFIS/05 - ASTRONOMIA E ASTROFISICA