Multi-messenger observations of a binary neutron star merger
Source
Astrophysical Journal Letters
ISSN
20418205
Date Issued
2017-01-01
Author(s)
Abbott, B. P.
Abbott, R.
Abbott, T. D.
Acernese, F.
Ackley, K.
Adams, C.
Adams, T.
Addesso, P.
Adhikari, R. X.
Adya, V. B.
Affeldt, C.
Afrough, M.
Agarwal, B.
Agathos, M.
Agatsuma, K.
Aggarwal, N.
Aguiar, O. D.
Aiello, L.
Ain, A.
Ajith, P.
Allen, B.
Allen, G.
Allocca, A.
Altin, P. A.
Amato, A.
Ananyeva, A.
Anderson, S. B.
Anderson, W. G.
Angelova, S. V.
Antier, S.
Appert, S.
Arai, K.
Araya, M. C.
Areeda, J. S.
Arnaud, N.
Arun, K. G.
Ascenzi, S.
Ashton, G.
Ast, M.
Aston, S. M.
Astone, P.
Atallah, D. V.
Aufmuth, P.
Aulbert, C.
AultONeal, K.
Austin, C.
Avila-Alvarez, A.
Babak, S.
Bacon, P.
Bader, M. K.M.
Bae, S.
Baker, P. T.
Baldaccini, F.
Ballardin, G.
Ballmer, S. W.
Banagiri, S.
Barayoga, J. C.
Barclay, S. E.
Barish, B. C.
Barker, D.
Barkett, K.
Barone, F.
Barr, B.
Barsotti, L.
Barsuglia, M.
Barta, D.
Barthelmy, S. D.
Bartlett, J.
Bartos, I.
Bassiri, R.
Basti, A.
Batch, J. C.
Bawaj, M.
Bayley, J. C.
Bazzan, M.
Bécsy, B.
Beer, C.
Bejger, M.
Belahcene, I.
Bell, A. S.
Berger, B. K.
Bergmann, G.
Bero, J. J.
Berry, C. P.L.
Bersanetti, D.
Bertolini, A.
Betzwieser, J.
Bhagwat, S.
Bhandare, R.
Bilenko, I. A.
Billingsley, G.
Billman, C. R.
Birch, J.
Birney, R.
Birnholtz, O.
Biscans, S.
Biscoveanu, S.
Bisht, A.
Bitossi, M.
Biwer, C.
Abstract
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 deg<sup>2</sup> at a luminosity distance of 40<inf>-</inf> <sup>+</sup> <inf>8</inf> <sup>8</sup> 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.
Subjects
Gravitational waves | Stars: neutron