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.



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.

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About Glen Mark Martin

MCSE-Messaging. Exchange Administrator at the University of Texas at Austin. Unrepentant armchair physicist.
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