LIGO Scientific Collaboration collab. clb IRD Virgo Collaboration collab. clb IRD Pierre Auger Collaboration collab. clb IRD et al. auteur aut IRD Hello Yann collab. clb IRD text journalArticle eng text/pdf reformatted digital access On 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 similar to 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 deg(2) at a luminosity distance of 40(-8)(+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-circle dot. 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 similar to 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 similar to 10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position similar to 9 and similar to 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 NGC4993 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. specialized gravitational waves stars: neutron 060 020 032 848 2 L12 [59 p.] 2017 2041-8205 https://www.documentation.ird.fr/hor/fdi:010071328 10.3847/2041-8213/aa91c9 2041-8205 [F B010071328] https://www.documentation.ird.fr/hor/fdi:010071328 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-11/010071328.pdf IRD - Base Horizon / Pleins textes 2017-12-04 2023-07-11 fdi:010071328 fre