Nav: Home

Gravitational waves detected for a second time

June 15, 2016

On December 26, 2015, at 03:38:53 UTC, scientists observed gravitational waves--ripples in the fabric of spacetime--for the second time.

Both of the twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors--located in Livingston, Louisiana, and Hanford, Washington--detected the gravitational wave event, named GW151226. The LIGO Scientific Collaboration (LSC) and the Virgo Collaboration used data from the twin LIGO detectors to make the discovery, which is accepted for publication in the journal Physical Review Letters.

Gravitational waves carry information about their origins and about the nature of gravity that cannot otherwise be obtained. Physicists on the LIGO and Virgo teams concluded that the final moments of a black hole merger produced the gravitational waves observed on December 26, 2015.

LIGO's historic first detection on September 14, 2015 resulted from a merger of two black holes 36 and 29 times the mass of the sun. In contrast, the black holes that created the second event were relative flyweights, tipping the scales at 14 and eight times the mass of the sun. Their merger produced a single, more massive spinning black hole that is 21 times the mass of the sun, and transformed an additional sun's worth of mass into gravitational energy.

"It's fabulous that our waveform models have pulled out from the noise such a weak but incredibly valuable gravitational wave signal," said Alessandra Buonanno, a UMD College Park Professor of Physics and LSC principal investigator who also has an appointment as Director at the Max Planck Institute for Gravitational Physics in Potsdam, Germany. Buonanno has led the effort to develop highly accurate models of gravitational waves that black holes would generate in the final process of orbiting and colliding with each other.

"GW151226 perfectly matches our theoretical predictions for how two black holes move around each other for several tens of orbits and ultimately merge," Buonanno added. "Remarkably, we could also infer that at least one of the two black holes in the binary was spinning."

The merger occurred approximately 1.4 billion years ago. The detected signal comes from the last 27 orbits of the black holes before their merger. Based on the arrival time of the signals--the Livingston detector measured the waves 1.1 milliseconds before the Hanford detector--researchers can roughly determine the position of the source in the sky.

"It is very significant that these black holes were much less massive than those observed in the first detection," said Gabriela Gonzalez, LSC spokesperson and professor of physics and astronomy at Louisiana State University. "Because of their lighter masses compared to the first detection, they spent more time--about one second--in the sensitive band of the detectors. It is a promising start to mapping the populations of black holes in our universe."

The first detection of gravitational waves, announced on February 11, 2016, was a milestone in physics and astronomy. It confirmed a major prediction of Albert Einstein's 1915 general theory of relativity and marked the beginning of the new field of gravitational wave astronomy.

"We could tell within minutes that GW151226 was very likely a real event. We all just marveled at it for a while," said Peter Shawhan, an associate professor of physics at UMD and an LSC principal investigator. "By December we were sure that the first event was genuine and we had a fairly mature draft of that paper, which finally came out in February. But it was very satisfying to know, even then, that we already had a second event on our hands."

The second discovery "has truly put the 'O' for Observatory in LIGO," said Albert Lazzarini, deputy director of the LIGO Laboratory at Caltech. "With detections of two strong events in the four months of our first observing run, we can begin to make predictions about how often we might be hearing gravitational waves in the future. LIGO is bringing us a new way to observe some of the darkest yet most energetic events in our universe."

Both discoveries resulted from the enhanced capabilities of Advanced LIGO, a major upgrade that increased the sensitivity of the instruments and the volume of the universe probed compared with the first-generation LIGO detectors.

Advanced LIGO's next data-taking run will begin this fall. By then, scientists expect further improvements in detector sensitivity could allow LIGO to reach as much as 1.5 to two times more of the volume of the universe compared with the first run, which has already resulted in two major findings.

The Virgo detector, a third interferometer located near Pisa, Italy, with a design similar to the twin LIGO detectors, is expected to come online during the latter half of LIGO's upcoming observation run. Virgo will improve physicists' ability to locate the source of each new event, by comparing millisecond-scale differences in the arrival time of incoming gravitational wave signals.
-end-
The research paper, "GW151226: Observation of Gravitational Waves from a 22 Solar-mass Binary Black Hole Coalescence," by the LIGO Scientific Collaboration and the Virgo Collaboration, has been accepted for publication in the journal Physical Review Letters.

About LIGO and Virgo

LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1,000 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 LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. NSF 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, the ARCCA cluster at Cardiff University, the University of Wisconsin-Milwaukee, and the Open Science Grid. Several universities designed, built, and tested key components and techniques for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Western Australia, the University of Florida, Stanford University, Columbia University in the City of New York, and Louisiana State University. 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 Germany, and the University of the Balearic Islands in Spain.

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.

Media Relations Contact: Matthew Wright, 301-405-9267, mewright@umd.edu

University of Maryland
College of Computer, Mathematical, and Natural Sciences
2300 Symons Hall
College Park, MD 20742
http://www.cmns.umd.edu
@UMDscience

About the College of Computer, Mathematical, and Natural Sciences

The College of Computer, Mathematical, and Natural Sciences at the University of Maryland educates more than 7,000 future scientific leaders in its undergraduate and graduate programs each year. The college's 10 departments and more than a dozen interdisciplinary research centers foster scientific discovery with annual sponsored research funding exceeding $150 million.

University of Maryland

Related Black Holes Articles:

Growing old together: A sharper look at black holes and their host galaxies
The 'special relationship' between supermassive black holes (SMBHs) and their hosts -- something astronomers and physicists have observed for quite a while -- can now be understood as a bond that begins early in a galaxy's formation and has a say in how both the galaxy and the SMBH at its center grow over time, according to a new study from Yale University.
Are black holes made of dark energy?
Two University of Hawaii at Manoa researchers have identified and corrected a subtle error that was made when applying Einstein's equations to model the growth of the universe.
Pair of supermassive black holes discovered on a collision course
Astronomers have spotted a pair of supermassive black holes on a collision course in a galaxy 2.5 billion light-years away.
Telescopes in space for even sharper images of black holes
Astronomers have just managed to take the first image of a black hole, and now the next challenge facing them is how to take even sharper images, so that Einstein's Theory of General Relativity can be tested.
Can entangled qubits be used to probe black holes?
Information escapes from black holes via Hawking radiation, so it should be possible to capture it and use it to reconstruct what fell in: if given time longer than the age of the universe.
How black holes power plasma jets
Cosmic robbery powers the jets streaming from a black hole, new simulations reveal.
The orderly chaos of black holes
During the formation of a black hole a bright burst of very energetic light in the form of gamma-rays is produced, these events are called gamma-ray bursts.
Mystery of coronae around supermassive black holes deepens
Researchers have used observations from the ALMA radio observatory to measure, for the first time, the strength of magnetic fields near two supermassive black holes at the centers of an important type of active galaxies.
Supermassive black holes and supercomputers
The universe's deep past is beyond the reach of even the mighty Hubble Space Telescope.
Black holes really just ever-growing balls of string, researchers say
Black holes aren't surrounded by a burning ring of fire after all, suggests new research.
More Black Holes News and Black Holes Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.