Abbott, B. P.B. P.AbbottAbbott, R.R.AbbottAbbott, T. D.T. D.AbbottAcernese, F.F.AcerneseAckley, K.K.AckleyAdams, C.C.AdamsAdams, T.T.AdamsAddesso, P.P.AddessoAdhikari, R. X.R. X.AdhikariAdya, V. B.V. B.AdyaAffeldt, C.C.AffeldtAfrough, M.M.AfroughAgarwal, B.B.AgarwalAgathos, M.M.AgathosAgatsuma, K.K.AgatsumaAggarwal, N.N.AggarwalAguiar, O. D.O. D.AguiarAiello, L.L.AielloAin, A.A.AinAjith, P.P.AjithAllen, B.B.AllenAllen, G.G.AllenAllocca, A.A.AlloccaAltin, P. A.P. A.AltinAmato, A.A.AmatoAnanyeva, A.A.AnanyevaAnderson, S. B.S. B.AndersonAnderson, W. G.W. G.AndersonAngelova, S. V.S. V.AngelovaAntier, S.S.AntierAppert, S.S.AppertArai, K.K.AraiAraya, M. C.M. C.ArayaAreeda, J. S.J. S.AreedaArnaud, N.N.ArnaudArun, K. G.K. G.ArunAscenzi, S.S.AscenziAshton, G.G.AshtonAst, M.M.AstAston, S. M.S. M.AstonAstone, P.P.AstoneAtallah, D. V.D. V.AtallahAufmuth, P.P.AufmuthAulbert, C.C.AulbertAultONeal, K.K.AultONealAustin, C.C.AustinAvila-Alvarez, A.A.Avila-AlvarezBabak, S.S.BabakBacon, P.P.BaconBader, M. K.M.M. K.M.BaderBae, S.S.BaeBaker, P. T.P. T.BakerBaldaccini, F.F.BaldacciniBallardin, G.G.BallardinBallmer, S. W.S. W.BallmerBanagiri, S.S.BanagiriBarayoga, J. C.J. C.BarayogaBarclay, S. E.S. E.BarclayBarish, B. C.B. C.BarishBarker, D.D.BarkerBarkett, K.K.BarkettBarone, F.F.BaroneBarr, B.B.BarrBarsotti, L.L.BarsottiBarsuglia, M.M.BarsugliaBarta, D.D.BartaBarthelmy, S. D.S. D.BarthelmyBartlett, J.J.BartlettBartos, I.I.BartosBassiri, R.R.BassiriBasti, A.A.BastiBatch, J. C.J. C.BatchBawaj, M.M.BawajBayley, J. C.J. C.BayleyBazzan, M.M.BazzanBécsy, B.B.BécsyBeer, C.C.BeerBejger, M.M.BejgerBelahcene, I.I.BelahceneBell, A. S.A. S.BellBerger, B. K.B. K.BergerBergmann, G.G.BergmannBero, J. J.J. J.BeroBerry, C. P.L.C. P.L.BerryBersanetti, D.D.BersanettiBertolini, A.A.BertoliniBetzwieser, J.J.BetzwieserBhagwat, S.S.BhagwatBhandare, R.R.BhandareBilenko, I. A.I. A.BilenkoBillingsley, G.G.BillingsleyBillman, C. R.C. R.BillmanBirch, J.J.BirchBirney, R.R.BirneyBirnholtz, O.O.BirnholtzBiscans, S.S.BiscansBiscoveanu, S.S.BiscoveanuBisht, A.A.BishtBitossi, M.M.BitossiBiwer, C.C.Biwer2025-08-302025-08-302017-01-0110.3847/2041-8213/aa91c92-s2.0-85037171677http://repository.iitgn.ac.in/handle/IITG2025/22597On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg² at a luminosity distance of 40<inf>-</inf> ⁺ <inf>8</inf> ⁸ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 M<inf>☉</inf>. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.trueGravitational waves | Stars: neutronArticlehttps://iopscience.iop.org/article/10.3847/2041-8213/aa91c9/pdf204182131 January 20173408L12arJournal3296