Multi-messenger Observations of a Binary Neutron Star Merger

LIGO SCIENTIFIC COLLABORATION AND VIRGO COLLABORATION, FERMI GBM, INTEGRAL, ICECUBE COLLABORATION, ..., THE PIERRE AUGER COLLABORATION, ..., INCLUYENDO S. MOLLERACH

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2017 vol. 848

0004-637X

On 2017 August 17 a binary neutron star coalescence candidate (laterdesignated GW170817) with merger time 12:41:04 UTC was observed throughgravitational waves by the Advanced LIGO and Advanced Virgo detectors.The Fermi Gamma-ray Burst Monitor independently detected a gamma-rayburst (GRB 170817A) with a time delay of ? 1.7 {{s}} with respect tothe merger time. From the gravitational-wave signal, the source wasinitially localized to a sky region of 31 deg2 at aluminosity distance of {40}-8+8 Mpc and withcomponent masses consistent with neutron stars. The component masseswere later measured to be in the range 0.86 to 2.26 {M}⊙. An extensive observing campaign was launched across theelectromagnetic spectrum leading to the discovery of a bright opticaltransient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC4993 (at ? 40 {{Mpc}}) less than 11 hours after the merger by theOne-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. Theoptical transient was independently detected by multiple teams within anhour. Subsequent observations targeted the object and its environment.Early ultraviolet observations revealed a blue transient that fadedwithin 48 hours. Optical and infrared observations showed a redwardevolution over ?10 days. Following early non-detections, X-ray andradio emission were discovered at the transient´s position ? 9and ? 16 days, respectively, after the merger. Both the X-ray andradio emission likely arise from a physical process that is distinctfrom the one that generates the UV/optical/near-infrared emission. Noultra-high-energy gamma-rays and no neutrino candidates consistent withthe source were found in follow-up searches. These observations supportthe hypothesis that GW170817 was produced by the merger of two neutronstars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) anda kilonova/macronova powered by the radioactive decay of r-processnuclei synthesized in the ejecta.