PULLMAN, Wash. – For the first time, scientists have observed ripples in the fabric of space-time called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.
Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.
The gravitational waves were detected on Sept. 14, 2015, at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, La., and Hanford, Wash., USA. The LIGO observatories are funded by the National Science Foundation (NSF), and were conceived, built and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.
WSU work enhances detection
WSU scientists contributing to the discovery are professor Sukanta Bose, postdoctoral researcher Nairwita Mazumder and graduate students Bernard Hall and Ryan Magee – all physicists; and astrophysicists Fred Raab and Greg Mendell, who are WSU adjunct faculty working at LIGO at Hanford.
“In addition to dramatically confirming Einstein’s general theory of relativity, this marks the beginning of a new era in astrophysics,” said Matt McCluskey, WSU physics and astronomy chair. “We now have a working gravitational wave observatory, and WSU is in on the ground floor.”
Bose and his collaborators and students laid the foundation for combining data from multiple detectors to increase the chance of discovering a gravitational wave signal. They also worked on the method for searching gravitational-wave signals from black hole mergers, aided by prior research by WSU theoretical physicist Matt Duez.
Mazumder, Hall and Magee contributed to a better understanding of the detector’s behavior, helping it see deeper into the universe. They benefited from regular interactions with Raab and Mendell at LIGO.
The media and public are invited to meet at 11 a.m. today in Webster Hall 17 for a discussion of WSU’s role in the discovery.
Third LIGO proposed to improve accuracy
Bose is working with a team of U.S. and Indian scientists on a proposal to build an additional detector in India.
“A third LIGO detector far away from the two in the United States will allow astronomers to localize powerful gravitational wave events more accurately in the sky,” he said. “This discovery closes one important chapter in Einstein’s theory of gravity but opens a whole new one that promises to be equally fascinating, if not more.
“It involves using telescopes to spot optical, X-ray and radio counterparts to observe the gravitational wave sources that emit them,” he said. “Combining information channeled through both gravitational wave and electromagnetic observations can teach us much more about these distant violent events in the universe than what any one type of observation can do. It will be an exciting ride.”
Bose is scheduled to talk about the discovery at 4 p.m. Tuesday, Feb. 16, in Webster 17 at WSU Pullman. More information on gravitational wave research at WSU can be found at http://pleiades.physics.wsu.edu/.
More about LIGO
The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run. The US National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project. Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin-Milwaukee. Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of the City of New York, and Louisiana State University.
LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom, and the University of the Balearic Islands in Spain.
LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech.
Virgo research is carried out by the Virgo Collaboration, consisting of more than 250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.
Sukanta Bose, WSU physics department, firstname.lastname@example.org
Nairwita Mazumder, WSU physics department, 432-271-6536, email@example.com
Fred Raab, WSU adjunct faculty at LIGO in Hanford, firstname.lastname@example.org