LIGO Does It Again!

Hot on the heels of the LIGO founders being awarded the 2017 Nobel Prize in Physics, the LIGO/VIRGO collaboration, in conjunction with the ESO, have struck gold again. After four detections of gravitational waves from black hole-black hole collisions, LIGO has detected what it was originally designed to detect: the merger of two neutron stars.  What’s more, as a bonus, the collision has also been observed in the EM spectrum by multiple astronomy teams around the world in the gamma, X-ray, UV, visible, IR, and radio portions of the spectrum.  Analysis of the data gathered by these observations indicates what was expected: the large-scale production of heavy nuclei.

We have well and truly entered the era of multi-messenger astronomy.

Alas, the IceCube Neutrino Observatory did not detect any accompanying neutrinos from this event, which would have been something of a trifecta.  IceCube researchers point out that this result is not surprising given that we are well off-axis from any jets produced by this event. Left unsaid by the researchers is the fact that, at a distance of 130 million light-years away, this event was substantially further away than what was arguably the first multi-messenger astronomy event, the detection (optically and via neutrinos) of supernova SN1987a, which, at a distance of a mere 168,000 light years, was practically next door by cosmological standards and resulted in the detection of only a handful of neutrino events.

Papers

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral (open access)
  Published in Phys. Rev. Lett. 119, 161101 (2017)
• GW170817 Data Release
• Multi-Messenger Observations of a Binary Neutron Star Merger (open access)
  Published in Astrophys. J. Lett.
• Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB170817A(open access)
  Published in Astrophys. J. Lett.
• A Gravitational-Wave Standard Siren Measurement of the Hubble Constant (currently free to read)
  Published in Nature
• Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
  Accepted by Astrophys. J. Lett.
• GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences
  Submitted to Phys. Rev. Lett.
• On the Progenitor of Binary Neutron Star Merger GW170817
  Accepted by Astrophys. J. Lett.
• Search for High-energy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory (authored by the ANTARES, IceCube, Pierre Auger, LIGO Scientific, and Virgo Collaborations)
  Submitted to Astrophys. J. Lett.
• Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger, by E. Pian et al. in Nature.
• The emergence of a lanthanide-rich kilonova following the merger of two neutron stars, by N. R. Tanvir et al. in Astrophysical Journal Letters
• The electromagnetic counterpart to a gravitational wave source unveils a kilonova, by S. J. Smartt et al. in Nature
• The unpolarized macronova associated with the gravitational wave event GW170817, by S. Covino et al. in Nature Astronomy
• The Distance to NGC 4993 — The host galaxy of the gravitational wave event GW17017, by J. Hjorth et al. in Astrophysical Journal Letters
• The environment of the binary neutron star merger GW170817, by A. J. Levan et al. in Astrophysical Journal Letters

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LIGO/Virgo detected the event (dubbed GW170817) on 17 August 2017.  Two seconds later, both the Fermi Gamma-ray Space Telescope (operated by NASA) and INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL) (operated by the ESA) detected a gamma ray burst from the same area. Around the world, telescopes swung into action to observe that part of the sky, including VISTA, VST, REM, LCO, DECam, Swope, Pan-STARRS, and Subaru.  Soon, the search was narrowed down to a point of light near galaxy NGC 4993. Subsequent observations were also carried out by VLT, NTT, MPG/ESO, ALMA, ePESSTO, the Hubble Space Telescope, and many others. Spectroscopic analysis of ejecta from the kilonova is consistent with large-scale r-process nucleosynthesis, consistent with theoretical models of neutron star mergers.

For More Information

• ESO Telescopes Observe First Light from Gravitational Wave Source | ESO
• GW170817 – THE FIRST OBSERVATION OF GRAVITATIONAL-WAVES FROM A BINARY NEUTRON STAR INSPIRAL | LIGO
• NASA Missions Catch First Light from a Gravitational-Wave Event | NASA
• LIGO and Virgo make first detection of gravitational waves produced by colliding neutron stars – Discovery marks first cosmic event observed in both gravitational waves and light. | LIGO
• NASA Missions Catch First Light From a Gravitational-Wave Event | HubbleSite
• Standard Sirens | Preposterous Universe
• Viewpoint: Neutron Star Merger Seen and Heard | APS Physics
• Kilonovae, short gamma-ray bursts & neutron star mergers | Nature
• Colliding stars spark rush to solve cosmic mysteries | Nature
• No neutrino emission from a binary neutron star merger | IceCube
• The era of multimessenger astronomy begins | Physics Today
• First observation of gravitational waves from merging neutron stars | Max Planck Institute
• A Scientific Breakthrough! Combining Gravitational and Electromagnetic Waves | Of Particular Significance
• Scientists observe first verified neutron-star collision | Symmetry
• Neutron star collision sparks new era of discovery | PI: Inside the Perimeter
• BIG NEWS: FOR THE FIRST TIME, ASTRONOMERS DETECT GRAVITATIONAL WAVES FROM TWO NEUTRON STARS CRASHING TOGETHER! | Phil Plait
• For The First Time, Astronomers Observed The Merging Of Neutron Stars | Starts With A Bang
• A Neutron Star Collision: Gamma Rays & Gravitational Waves | Physics Buzz
• Spectacular collision of two neutron stars observed for first time | IOP PhysicsWorld.com
• IOP hails detection of gravitational waves from collision of neutron stars | IOP
• Neutron star smashup seen for first time, ‘transforms’ understanding of Universe | Phys.org
• Neutron star collision showers the universe with a wealth of discoveries | ScienceNews