3 December 2018
Four new gravitational wave detections announced today include the most massive and distant source ever observed.
The results are included in a new paper from the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the VIRGO gravitational-wave detector, which presents analysis of 10 stellar-mass binary black hole mergers and one neutron star merger.
Professor Sheila Rowan is Director of the University of Glasgow’s Institute for Gravitational Research. Professor Rowan said: “This remarkable crop of detections show just how valuable gravitational wave astronomy is in developing our understanding of the universe.
“In less than three years gravitational wave detections have given us direct evidence of the existence of black holes and binary neutron star collisions. Today we present a wealth of new data from LIGO and Virgo to stand alongside the ground-breaking discoveries already made during their initial observing runs. It took science a century to confirm Einstein’s prediction of the existence of gravitational waves, but the pace of our discoveries since then has been exhilarating, and we’re anticipating many more exciting detections to come.”
From September 12, 2015, to January 19, 2016, during the first LIGO observing run since undergoing upgrades in a program called Advanced LIGO, gravitational waves from three binary black hole mergers were detected.
The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded a binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational wave events being reported now. The new events are known as GW170729, GW170809, GW170818 and GW170823 based on the dates on which they were detected.
The new event GW170729, detected in the second observing run on July 29, 2017, is the most massive and distant gravitational-wave source ever observed. In this coalescence, which happened roughly 5 billion years ago, an equivalent energy of almost five solar masses was converted into gravitational radiation.
Since the detectors first started operation in September 2015, the LIGO and Virgo Collaborations, which include the Universities of Birmingham, Cardiff and Glasgow and also the University of Strathclyde, have completed two observation runs. During these runs they have detected gravitational waves from a total of ten stellar-mass binary black hole mergers – compact objects likely formed by the gravitational collapse of massive stars. They have also detected one binary neutron star coalescence – generated by two neutron stars spiraling into each other.
The two observing runs carried out by the LIGO and Virgo Collaborations were: O1, from September 12, 2015 to January 19, 2016; and O2, from November 30, 2016 to August 25, 2017.
The detections were made by the global network formed by the LIGO observatories located in Livingston, Louisiana, and Hanford, Washington, USA, and the Virgo interferometer near Pisa, Italy.
The scientific paper describing these new findings presents detailed information in the form of a catalog of all the gravitational wave detections and candidate events of the two observing runs. Thanks to more advanced data processing and better calibration of the instruments, the accuracy of the astrophysical parameters of the previously announced events increased considerably.
The LIGO Scientific Collaboration and the Virgo Collaboration, “GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs”
The LIGO Scientific Collaboration and the Virgo Collaboration, “Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo”
The UK’s involvement with Gravitational Waves research is led by the Universities of Birmingham, Cardiff and Glasgow and also supported by the University of Strathclyde.
LIGO is funded by the National Science Foundation and operated by Caltech and MIT, which conceived and built the project. Financial support for the Advanced LIGO project was led by NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at on the Ligo website.
The Virgo collaboration consists of more than 300 physicists and engineers belonging to 28 different European research groups. A list of the Virgo Collaboration can be found online. More information is available on the Virgo website.
Further quotes from UK researchers involved in this work can be viewed on a PDF document (PDF, 144 KB).
Last updated: 03 December 2018