Multi-Messenger Observations of a Binary Neutron Star Merger
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 approx. 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 40-8+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 . 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 approx. 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 approx.10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position approx 9 and approx 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 16, 2017
- Accession Number
- AD1105707
Entities
People
- A. Chekhtman
- B. Agarwal
- B. P. Abbott
- C. Adams
- C. Affeldt
- Dario Gasparrini
- F. Acernese
- K. Ackley
- M. Afrough
- M. N. Lovellette
- Namir Kassim
- P. Addesso
- R. Abbott
- R. X. Adhikari
- Simona Giacintucci
- T. Adams
- T. D. Abbott
- T. E. Clarke
- V. B. Adya
- W. M. Peters
Organizations
- United States Naval Research Laboratory