Four New Gravitational Wave Detections Announced

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Gravitational Wave Detections

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.

Quotes from UK Scientists

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."

Professor Martin Hendry is head of the University of Glasgow's School of Physics and Astronomy. Professor Hendry added: "The four new detections discussed in this paper are exciting, particularly the largest and most distant black hole collision we've seen to date, but what's equally significant is that we now have data from 11 detections collected together as a catalogue. That represents a big step forward in our understanding of the universe, and is a ringing endorsement of the effectiveness of gravitational wave astronomy."

Professor Alberto Vecchio, from the University of Birmingham's Institute for Gravitational Wave Astronomy, said, "It's a universe full of black holes: they pair up and collide, and they do it very frequently. Advanced LIGO has started to operate as an astronomical observatory providing us with a steady stream of new discoveries. The scene is now set to begin understanding the cosmos' black hole factories. Three years ago only a fool would have thought we would be under a deluge of binary black holes, but now this is an intoxicating reality. And it is just the beginning."

Professor Andreas Freise, from the University of Birmingham's Institute for Gravitational Wave Astronomy, said, "When black holes collide they create vibrations in space and time. Now we know that this happens often: the LIGO detectors regularly detect faint echoes that tell of the last seconds in the life of a pair of black holes. These whispers from dark skies tell us about the size and the location of the dying black holes. We have become gravitational wave astronomers, creating new maps of the universe."

Riccardo Busciccchio, a Birmingham PhD student and member of the LIGO team, said, "We have a graveyard of 10 binary black holes that tells us a lot about their extreme violent last fractions of a second of life, and carry at the same time the signatures of their entire life both as individuals and as binary companions. As a PhD student, it has been a unique opportunity to have access to observations that are still so rare, and to study their characteristics as part of a clearly large population. You get so much enthusiasm, from learning a lot to being able to participate actively in the production of scientific results of such great relevance."

Dr. Patricia Schmidt, a member of the Virgo Team who will be joining Birmingham's Physics faculty in January 2019, said, "At just 39 square degrees, the second triple-coincident binary black hole, GW170818, is the best localized binary black hole observed to date highlighting the importance of a global detector network. With almost a dozen confident gravitational-wave detections, we have truly established the field of gravitational-wave astronomy. The third observing run is on our doorstep. With an unprecedented number of gravitational-wave observations anticipated, the scientific prospects are enticing."

Professor Mark Hannam, from Cardiff University's School of Physics and Astronomy, said: "This is an exciting transition to making regular observations. With more than 10 detections, we are now starting to really understand the properties of the black holes in our universe."

Dr. Vivien Raymond, from Cardiff University's School of Physics and Astronomy, said: ""After the wonderful achievement of the first detection, the new field of Gravitational Astronomy is delivering on its promises. This very first catalogue represents our knowledge of the gravitational-wave Universe. And it will from now on increase tremendously both in size and complexity."

Professor Hartmut Grote, from Cardiff University's School of Physics and Astronomy, said: "It is exciting to see the fruits of decades of hard work on the instruments that facilitated all the detections. The instruments are now undergoing further improvements, to be ready for a new data taking run with unprecedented sensitivity starting in spring of 2019."

Professor Nicholas Lockerbie from the University of Strathclyde said "The two LIGO detectors in the USA, and the Virgo detector in Europe, have been decades in their conception, construction, bringing into operation, and refinement, requiring the work of more than 1000 scientists and engineers, internationally. Indeed, in collaboration with the Institute for Gravitational Research at the University of Glasgow, my colleagues and I in the Department of Physics at the University of Strathclyde have contributed to this effort. However, it is only a little over three years ago now that the very first direct detection of gravitation waves was ever made -- by LIGO -- the gravitational wave signal from two colliding Black Holes. It is also only just over one year ago that the very first gravitational wave signal from two colliding neutron stars was seen. Subsequently, this event was recorded by telescopes and various types of detector right across the electromagnetic spectrum, and it marked the beginning of true 'multi-messenger' astronomy. It even provided a possible explanation for the origin of much of the gold and heavy elements in the universe! The work which is about to be published, and which catalogues the results from the first two observing runs, demonstrates the unparalleled capability of this ground-breaking gravitational-wave network to make new science. The systematic exploitation of the scientific output from these gravitational wave observatories is a now a reality."

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