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Multi-messenger observations of a binary neutron star merger

  • Author(s): Abbott, BP
  • Abbott, R
  • Abbott, TD
  • Acernese, F
  • Ackley, K
  • Adams, C
  • Adams, T
  • Addesso, P
  • Adhikari, RX
  • Adya, VB
  • Affeldt, C
  • Afrough, M
  • Agarwal, B
  • Agathos, M
  • Agatsuma, K
  • Aggarwal, N
  • Aguiar, OD
  • Aiello, L
  • Ain, A
  • Ajith, P
  • Allen, B
  • Allen, G
  • Allocca, A
  • Altin, PA
  • Amato, A
  • Ananyeva, A
  • Anderson, SB
  • Anderson, WG
  • Angelova, SV
  • Antier, S
  • Appert, S
  • Arai, K
  • Araya, MC
  • Areeda, JS
  • Arnaud, N
  • Arun, KG
  • Ascenzi, S
  • Ashton, G
  • Ast, M
  • Aston, SM
  • Astone, P
  • Atallah, DV
  • Aufmuth, P
  • Aulbert, C
  • AultONeal, K
  • Austin, C
  • Avila-Alvarez, A
  • Babak, S
  • Bacon, P
  • Bader, MKM
  • Bae, S
  • Baker, PT
  • Baldaccini, F
  • Ballardin, G
  • Ballmer, SW
  • Banagiri, S
  • Barayoga, JC
  • Barclay, SE
  • Barish, BC
  • Barker, D
  • Barkett, K
  • Barone, F
  • Barr, B
  • Barsotti, L
  • Barsuglia, M
  • Barta, D
  • Barthelmy, SD
  • Bartlett, J
  • Bartos, I
  • Bassiri, R
  • Basti, A
  • Batch, JC
  • Bawaj, M
  • Bayley, JC
  • Bazzan, M
  • Bécsy, B
  • Beer, C
  • Bejger, M
  • Belahcene, I
  • Bell, AS
  • Berger, BK
  • Bergmann, G
  • Bero, JJ
  • Berry, CPL
  • Bersanetti, D
  • Bertolini, A
  • Betzwieser, J
  • Bhagwat, S
  • Bhandare, R
  • Bilenko, IA
  • Billingsley, G
  • Billman, CR
  • Birch, J
  • Birney, R
  • Birnholtz, O
  • Biscans, S
  • Biscoveanu, S
  • Bisht, A
  • Bitossi, M
  • Biwer, C
  • et al.
Abstract

© 2017. The American Astronomical Society. All rights reserved. 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 ~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-+88 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☉. 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.

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